I have an InfoPath form embedded in an aspx page on a SharePoint site. How do I bind the SharePoint user groups to a drop-down list on my form? What I've tried so far is to create a data connection to a web service (method GetGroupCollectionFromWeb) to pull the data. Next, I open the list box properties, select "Look up values from an external data source", select the data source, assign the entries, and I get the following error:

"You must select a repeating group or field."

What I don't understand is that since the method I am calling is called GetGroupCollectionFromWeb, isn't the return value a collection? And aren't collections repeating by definition? What am I missing, and is there a workaround? Thank you.