Hi Jon
Thank you very much for your help. and YES, Excel can give you just a bit of
headache (my boss can't understand what can be so complicate in calculating
the difference between hours!!!)
So what i've done may be not very clever and smart, but i made another
column for "undertime" and used formula
=IF(D13$B$11,0,B11-$D$13)
(so used your formula other way round )
seems to be it is working.
Thank you very much!
Svetlana