Button doesn't evaluate variable containing Module

I have a huge set of code to accomplish a data transformation. I have saved this set of code as eg:

 codeset:=Module[{},

            FileNameSetter[Dynamic[Tab2excelFileLocation]];
            RawDataTonnages =Import[Tab2excelFileLocation, {"Sheets", "Tonnages"}]; 
 (*...blah blah blah...data transformation and setting up graphs and stats tables...*)
            FileNameSetter[Dynamic[Tab3excelFileLocation]];
            Tab3RawDataTonnages =Import[Tab3excelFileLocation, {"Sheets", "Tonnages"}]
 (*...blah blah blah....data transformation and setting up graphs and stats tables...*)
            ];
 Button["Recalculate", codeset]

Later I want to use the two FileNameSetter buttons to locate new files. Once this has been done I then want to press the Recalculate button to re-evaluate 'codeset' so that my answers reflect the data from the new files.

I have get this to work partially - when I press the button the codeset re-evaluates for the 1st filename setter only even though I have changed both. If I test not by using the button but by re-evaluating the code using shift+enter it works for both filename setters. Why is this happening, I can't understand it.