I check to see if my hidden scteen is an object.

IF TYPE('myobj')='O'

An error occurs if the object is not defined.

Not so. If the object does not exist, TYPE( 'myobj') returns U.

It is VARTYPE that you must be careful with. If you are checking a member property such as:

VARTYPE( Thisform.myobj )

an error will occur if myobj is not defined as a property of the form.