Here is a Video we made to help you getting started.
The video introduces you to SupportDesk and shows you where to begin.

When you see a dialog with the message:

- 'Connection Status Login: Your helpdesk did not return any data (please check our knowledgebase)...'

or

'Connection Status Sync: Your helpdesk did not return any data (please check our knowledgebase)...'

it is obvious that something wrong.

When it is the first (Login) chances are that your credentials are incorrect. So the advise here is to check them in your helpdesk settings.

When it is the second (Sync) it is probably an expired session although this might sound strange. In this case you please make sure $disablesessionipcheck option in the config/config.php file on your Kayako server is set to true .
When you don't know where to look or how to do this it is best to contact Kayako support about this. They should be able to help you.

There are different reasons with different messages and different solutions.

The most important messages and 'solutions' are shown below. When the 'solutions' don't help please create a ticket so that we can do our best to help you.

'The connection failed with message...'
When you see this message SupportDesk shows you the (error) message returned from the server or the network informing you of the reason why the connection failed.

Solution: Depends on the error. Generally waiting for a while should be enough.

'The connection failed, please try again later...'
When you see this message the server or the network did not return any information. The only thing you can do is wait and try again.
When the issue persists you could try to restart SupportDesk and/or the iPhone.

Solution: Just wait and try again.

'The returned data could not be interpreted, please try again...'
This is a serious issue. It generally means that the server returned a reply that has no valid character encoding.
It can also mean that synchronizing the number of tickets/posts exceeds the memory allocated to SupportDesk (something that we can not influence).

Solution: You should check the database table collation (encoding) and the locale/en-us/en-us.php file to check that the encoding is UTF-8 (this article on the Kayako wiki gives you more information about what to do: http://wiki.kayako.com/display/DOCS/Changing+v3+database+encoding+to+UTF-8).
When that the encoding is ok you can disable statusses and see if that solves anything.
Generally a ticket count of 1000+ is too much, between 500 and 1000 it depends on the number of posts.

Please check the article: 'My SupportDesks has 500+ tickets, will it synchronize'

'Your session is expired, please try again...'
This can happen when the last sync was (too) long ago.

Solution: synchronize again.

'Please check the preferences settings...'
In this case your helpdesk settings (most likely username/password) are wrong.

Solution: correct your helpdesk settings.

'Parsing the xml data failed...'
'No valid information found...'
When any of these 2 messages is shown it means that SupportDesk received an answer from the server that was ok at first sight but turns out to be wrong after all.
It could mean that there is a ticket/post in your data that makes that the xml data is not closed properly (in which case SupportDesk can not read the xml data).
It can also mean that the number of tickets that need to be synchronized exceeds the memory allocated to SupportDesk (something that we can not influence).

Solution: You can disable statuses and see if that solves anything. Generally a ticket count of 1000+ is too much, between 500 and 1000 it depends on the number of posts.

Please check the article: 'How) can I turn off statuses that I don't want synced?'

When this does not help please check that you don't have any Junk or ofther mail with 'strange' characters in them. When you have them in your system please remove them.

When you have an issue with SupportDesk and you want to help us solving it you can use the iPhone Configuration Utility.
Below are the instructions.

On Mac
01. Download the iPhone Configuration Utility Installer for Mac OS X.
02. Install the iPhone Configuration Utility by (opening the dmg file and) double clicking the Installer;
03. Locate and open the iPhone Configuration Utility from YourMac/Applications/Utilities;
04. Attach your iPhone to your Mac;
Proceed with step 5...

On (Windows) PC
01. Download the iPhone Configuration Utility Installer for Windows.
02. Install the iPhone Configuration Utility by double clicking the Installer;
03. Locate and open the iPhone Configuration Utility from Start>iPhone-Configurationutility>iPhone-Configurationutility (name depends on language settings);
04. Attach your iPhone to your Windows PC;
Proceed with step 5...

05. Start the iPhone Configuration Utility
06. On startup the Utility will look for your iPhone and will show your iPhone under Library/Devices in the tree on the left;
07. Select Devices/'your iphone name' (somewhere at the bottom of the tree on the left);
08. Select the 'Console' tab on the tabpanel of your iPhone (far right);
09. When there is too much information you can click in the search field on the right. Otherwise proceed with step 11;
10. Enter 'SupportDesk' in the search field to eliminate cluttering information;
11. Start SupportDesk and you should see log entries appear in the console;
12. Please trigger the issue once (or more when you can);
13. You should see  (hopefully) additional output in the console;
14. Now click the button 'Save Log As...' and attach the saved log file to your (new) ticket;

Turning off a department that you don't want to synchronize is not really possible but there is a workaround.
 
Please read further in the article: (How) can I turn off a status that I don't want to synchronize?

This is caused by the below settings in the Kayako admin section when they are disabled.
Please set them to yes and the issue should be gone.

Home > Tickets > Manage Statuses > Your Status To Manage > Display In Main Ticket Listing

If enabled, tickets set to this status will be listed in the View All ticket listing. Note: Enabling this option will also cause all tickets with this status to be synchronized with any Kayako Mobile clients.