when i open the trail version, it says - ’ WinTab service not available’, and i am not able to work on it. please advice me as to the solution to my problem.
thanks in advance.
What a frustrating problem that was for me when I started out. Alls that means is your tablet is not connected. Connect it, and bam it goes away 
My tablet is conneted, even on restart. I am still getting this message. 
Drivers updated. Still having a problem!.. sigh
Its starting to crash my Z while I’m working.
This looks like a common problem with Wacom tablets.
The last time I had trouble with mine, uninstalling followed by an immediate reinstall wasn’t enough. All folders created by Wacom in the install location, and settings location (Users in Windows 7, Documents & Settings in Windows XP) needed to be deleted after uninstalling the Wacom software. More importantly, a reboot after uninstalling/deleting is a must. Reinstall the drivers only after rebooting, then reboot again once they’re reinstalled for good measure. I have the Tablet PC Components disabled in Windows 7 as well because its feature set was interfering, but that probably had nothing to do with it. Might be worth trying, though you’ll lose handwriting recognition.
Edit: Do you have your tablet plugged into a USB hub by any chance? I’ve read a lot of comments by Wacom representatives stating this can cause detection problems.