Toggling Graphics from a Global Container

In the example folder of FM7 Dev there is a file called "Asset Management" (see attached file). In the file there is a list form.

When I click on a list column name, the form sorts and a down triangle appears next to the column name. When I click on the column name again the column reverse sorts and the triangle now appears as an up triangle. If I go to another column in the list it also sorts in the same way and the triangle only appears there but not in the first column. I have figured out how to do the column click sorting but not how to control the triangle picture.

The database has a field that is a Global container with 2 repetitions which has the two triangle images. I have checked and rechecked my scripts and they match the original routine used in the example file. I am trying to use this routine in my own database and cannot figure out how these triangles are being controlled.

Anyone have a solution?

Thanks

Burt

AssetManagement.fp7.zip