Why NullBinary compilation error happens on this situation

Why NullBinary compilation error happens on this situation

I want to check if file upload object content is null.
I try to do an If with the following expression "Upload1.Content = NullBinary()", but gives incompatible data types compilation error. Why NullBinary doesn't work?, both sides are Binary Data.
I know BinaryData extension.

Thank you.
Hi Nelson,

It's an odd behavior of platform. I'm not sure, but I think the error message is wrong. It seems Nullbinary() returns a Binary, not a BinaryData datatype. It's weird, since the purpose of NullBinary() has no meaning.

You probaly already know this, but if you wish to check if the object content is null, you can use BinaryData extension to compare if it equal to NullBinary, or the lenght is equal 0.

Compare(ReportBin,NullBinary()) = True

If returns a Binary instead of Binary Data the function description is wrong.
Yeah, It was what I meant. The messages are wrong. However, this is only a guess... maybe someone in outsystems could explain it better.