In order to ensure a correct synchronization, BirdieSync needs that the time zones defined in Lightning and on the mobile are identical. So you must select the appropriate time zone in Lightning or BirdieSync options and set it also on the mobile in the clock settings.
But sometimes even after the time zone was selected in a similar way on both platforms, an alert can be displayed about a difference between the two time zones.
This is generally caused because of different daylight saving dates on the mobile and the desktop. For instance, the clock on the mobile moves one hour forward on October the 14th, while it's November the 4th in Lightning. Why these differences ? Because unfortunatelly, these dates or the rules to get them can sometimes change, as it was recently the case in America or in Brazil for instance.
These problems are temporary: just during the period where for instance the mobile is one hour forward and Lightning is not. In our example, this period would last from October the 14th to November the 4th.
The last version of Lightning generally includes updates regarding the definition of time zones, but not always because the changes were very recent. On the mobile, you have to install patches to install the latest update for time zones, especially if your mobile was bought some time ago.
So especially if you need updated time zones for America, Canada or Mexico, it is recommended to install a patch on the mobile as described on this page.
Now if you need an updated time zone for Brazil for instance, it is trickier. Actually, neither Lightning nor the mobile have the correct time zone definition (for 2007)... So if you keep for instance "SaoPaulo" in Lightning, you must try to find another time zone on the mobile which will temporarily match the Lightning time zone, knowing that Lightning will move one hour forward only November the 4th. For instance "Buenos Aires" which has no daylight saving time. Then you should switch back to "Brazil", on November the 4th.
But be cautious if you create an appointment on the mobile with a date after November the 4th, while you are with "Buenos Aires" time zone. It will move forward one hour, when you switch to "Brazil"...
If you also want to have your PC up to date regarding time zones, you may have a look to this page.
If you want to precisely analyze your time zone problem, please note the offset mentioned in the alert message raising from the task bar or checkout BirdieSync logs: build a log archive after the error with BirdieSync menu "Help/Archive log..." or Thunderbird menu "Tools/BirdieSync/Log archive..." if in 2.x. Then open it. In ThunderbirdService.log or SunbirdService.log, you should find an error like: "Time zone are different on device (offset = ...) and desktop (offset = ...)". It will mention the time zone offset in minutes for both the mobile device and Lightning. These offset include the daylight saving time.
You may check which value is correct by looking at a web site like time and date.com where you'll find the current hour and time zone definition (with dates of daylight saving time) for each town or country. Then you'll be able to see if the definition of the time zone is incorrect on the mobile device, in Lightning or both...