Thanks selvamani,
I've look into the issue further and it's because you only support string types for the SelectValueById
I should have been more specific I'm trying to select a value by key and the Key is an int.
I'm using an OData 3 data source, and the query generated to select the my customer object doesn't work to select an int
http://[server]:[port]/ApplicationData.svc/qry_CustomerByUser?ShowAllCustomers=1&$select=Name,Id&$filter=tolower(Id)%20eq%20%275%27 or ShowAllCustomers=1&$select=Name,Id&$filter=tolower(Id) eq '5'
http://[server]:[port]/ApplicationData.svc/qry_CustomerByUser?ShowAllCustomers=1&$select=Name,Id&$filter=Id%20eq%205 or ShowAllCustomers=1&$select=Name,Id&$filter=id eq 5