>I can not the Value_assign method to work with a checkbox control. When I click on the checkbox the value of the checkbox toggles true and false visually, but the value_assign does not fire. I have put a breakpoint in there, no dice, not even SET STEP ON works. Any ideas why it isn't working? Can anyone reproduce this behaviour with VFP6 SP4?

A value_assign won't work on any control.

AFAIK, when putting a value into a control, the Value property isn't getting set explicitly - e.g., thisform.chkTest.Value = .T. - so the Value_assign won't fire.