It is good if you share your packaged workbook (with sample data) with us. Otherwise it is very complicated for us to find a solution to your problem.
I had a similar error myself.
In my case this seemed to be due to having an underscore "_" in the calculation that sets the selection.
If parameter.Selection = 'Sign_up' then X END
returned the error, when I changed it to 'Sign-up' it worked fine.
strange, but I guess it is a special character of some sort.