Field does not display data from SAP

I have reimported a model from SAP where there's one new field 'VAT'. I have changed the custom controller so the new field is mapped there and finally I have mapped the field to the views controller.

On the view I have changed an existing Inputfield to show the content of VAT where it previously was showing the content of another field from the same model.

After having made that change no data is displayed in the field, even though the data is available from SAP. The same field was working fine before when it was set to display another value from SAP.

Did I forget to do something ???