This isn't a problem with IIS, it's actually working as designed. The default recordset uses a "Static" cursor. This means that you can browse the results, but you cannot change anything. Instead of using the default "Cursor Type" (Static), you need to open the recordset with the cursor "KeySet" or "Dynamic".
I personally have avoided using DWMX... so I can't really tell you how to do that, but if you're willing to get your hands into the code, I'm sure it would be relatively easy to correct.
In the meantime.. check out this post.. the issue is the same, and I explain how to open a recordset with a KeySet cursor:
http://dbforums.com/t913752.html