Null via SQL case statement not working

Hi folks,

I have a simple field XYZ that has null values and the null values display as a question mark.

Now I have SQL querying this field that looks like this;

SELECT

myTable.XYZ,

CASE WHEN myTable.XYZ is Null Then 0 else 1 End As MyFlag

FROM... ETC

Of course the first column displays all question marks as expected....

But MyFlag field instead of displaying a list of zero's I'm getting all question marks.

What am I missing here?

Thanks!

-Patrick