I had a similar issue and it took me a while to get this to work correctly for me.
You need to create a rule on the DDL that you created with the client names.
- Right Click the DDL and choose Rules > Manage Rules
- Click New > Action
- Click Add > Send Data To Web Part
A box should pop up and give you a reminder that the field needs to be promoted as a pass through parameter. I assume you have already done this or else you wouldn't have had the options in the web parts to connect them.
Publish your form.
Others have been hung up on this next issue . You will need to edit your InfoPath form web part and choose your form again to refresh it. It will not know that the form has been changed automatically.
You should be all set.
If you need a bit more detail on this kind of issue. I wrote up a blog posting with screenshots. You can find it on: http://www.matt-engel.com/2013/03/how-to-build-a-better-choice-filter-web-part-using-infopath-2010/
I hope this helps you out!