Why "(Null == Null)" is "Null" instead of logically "True"?

Null has no value so it isn't possible to compare Null with Null.

you need to use the IsNull() function to get a True/False check.

Note to people saying = means assignment here.

In VBA and almost certainly VB6 = is a test rather than assignment.

This is shown in a Microsoft example here:

http://msdn.microsoft.com/en-us/library/752y8abs(V...

In languages such as C++ == is used for equality tests but not in VB.

You used a single = operator which means you actually assigned the value of NULL to Null. Since NULL has no value, it returned False.

One = or two? Usually assignment evaluates to whatever you assigned from.

edit: screenshot says you're doing assignment, not comparison. That's your bug.