I am using the 2008 Expression Tester. My expression is REPLACE( @[User::StringVar],"JAN", "01" ). The content of the StringVar is 10OCT2010. The tool evaluates the expression as 10OCT2010. The expected result is empty string. As per the function design (http://msdn.microsoft.com/en-us/library/ms141196.aspx
) and function synopses in the tool it should return the empty string.