Question : Add time but only in working hours

Hi. EE
I have a form that includes a live clock. i want to click a button that populates a field of a time that is 3 hours from now! however if 3 hours from now is after 8pm then it ignores the hours between 8pm and 11am the followung day and adds it to the next day:
EG.
If you click a button at 3pm it puts in the field 6pm the same day
if you click the button at 5.30pm it would put 11.30am the next day.
if you click at 8pm it would put 2pm the next day

so my working clock would start at 11am and stop at 8pm then at 11am the next day it thinks this is just the next hour from the day before and ignores the hours inbetween.

Can anyone help?

Answer : Add time but only in working hours

Actually I was wrong about the 30 day period in my last post - all OEM System Builder disks now require activation following installation, this is either done by the OEM (you!) before supplying it to the customer or left so the end user gets the activation screen and the "Welcome to Windows" experience on first switching on the PC (they have to agree to the on-screen EULA). So this is normal behavior for the install CD you have.