Had the same issue at my shop and never resolved it. In fact, we scrapped the IBM provider altogether and use a third party driver called Sequelink.
It works fine and is a whole lot simpler to configure, just have to live in constant fear that IBM will come along with a patch or upgrade someday that will break it. I have a really old version thats been working for years, but you can check it out at:
http://www.datadirect.com/
I hope its okay to post the link here...I have no relationship with the company what so ever and in fact we jsut bought a bunch of licenses and didnt even purchase support for the product and have not had a reason to talk to them since!
Its always in the back of my mind though that we should try and use IBM's version since it seems logical that it would be better or at least safer, but it is such a chore to configure and then theres the issue we run into when using it with SQL server I just hate to fool with it.