Validation rule for minimum amount of time between the values in 2 fields

[sprtrmp]

OK access wizards, here's one for you. I am sure this will be easy for someone out there:



I have a form with 2 fields, "TimeStart," and "TimeEnd". That a user would use to input the time they arrived at work, and the time they left to go home. "TimeEnd" has to be at least 4 hours after "TimeStart". What would I need to use as a validation rule to make sure that the time entered in "TimeEnd" is at least 4 hours after "TimeStart"??

If "TimeEnd" is fewer that 4 hours later than "TimeStart", some event needs to take place (either a message box or the control would change color, but I haven't figured that part out yet).

But wait, there is more: it is entirely possible that "TimeStart" could be later than 9pm, and the validation rule needs to recognize the fact that 0100 is AFTER 2100... if that makes any kind of sense.

Thanks in advance for the help.

[CJ_London]

you really need start and end date fields as well, then you would have something like

if datediff("n",dateend+timeend,datestart+timestart)< (4*60) then msgbox "checking out too soon"