SQL Server Reporting Services - Check For Null Column Value in an expression.
The following method can be used to check to see if a field value is null. After fiddling around with IsDbnull which will not raise an error but which will also not work I found that IsNothing will correctly check for a null value.
Place this as the expression in a Reporting Services Textbox:
=Iif(IsNothing(Fields!ANYFIELD.Value),"The Field Is Null",Fields!ANYFIELD.Value)