I create a form and use a public variable oCustbals to reference it. I initialise oCustbals = .NULL.

Later if I want to trigger the Activate method in the custbals form from another form I use this methology
IF NOT IsNull("oCustbals")
oCustbals.Activate
ENDIF
Sometimes I get an error stating oCustbals is not an object when oCustbals is showing in the debug window as .NULL. and Isnull(oCustbals) shows as .T.
Even if I use the following code the wait window is ignored:
oCustbals = .NULL.
IF IsNull("oCustbals")
wait window
ENDIF