Hello Paul,
Could you please try to upload again your attachment, because we didin`t received it. Please zip your file and using "Insert Madia" button (during you are replay to this post ) to attache it again or using "Option" tab to attached your files.
Thanks and Regards
Attached is the screen shot.
I try to reproduce your scenario in a small sample. Could you please take a look at the attached project for more details and let me know if you have any questions,
Regrads
Have you been able to resolve your issue ? Did you have a time to take a look at the attached sample. Let me know if you have any questions.
Regards