Hi what i found from your qvw file.
In this expression what ever the variable value ur providing that is not matching with the variance lookup value.
so qv is gving the null values ,if you test the expression with values it will work..
When you goto the variable overview add an = sign to the expression
Thanks for your quick response - I mocked up fictious data in this example so I expect to find some issues with null values but even if I add the value "10" to the Lookup Table, it still comes back with null in the yellow column for all rows. I need it to return "40" for the row with the value of "C" and null or 0 for all other rows since they don't have a match to the Lookup.