Sorry If I answer always in my post, but I wanna notify who wants to help me, with all my discoveries.
Ok...
The problem is in the condition (until now). I'm checking both variable: time and prevcheck.
Time value is linked to posttime that every time is setted to: servertime+boardoffset.
N.B. Is not better record the real time, and offset it at "select query" time?
However... i come back to code

I hope to be near!
Ultimate note:
Ehy Guys! 1189813460-1189806297=7163 near 2 hours!
My joomla server time is UTC + 2 (and however is wrong coz should be 1)
My Forum Board time is 0
....mmmmm.......