All of a sudden I started seeing the following error in the InfoPath form. I was editing a list edit form with InfoPath in SharePoint 2010. My problem was when I tried to create a new item, I couldn't type in any of the controls. I could set the focus of the cursor in the control, but I could type. In the InfoPath form I was seeing "Control bound to missing field or group". Not knowing what that meant, when I clicked "More Info" I got the following message:
"The selected control cannot store data because it is bound to a field or group that will not be included by default when a new form is created. To fix this problem, move the control into an optional section which is bound to the group that contains the controls field or group."
Not sure why it happened... I certainly don't remember changing anything, but after an hour or so I fixed the problem by realizing the data connection wasn't bringing back any data. What you need to do to fix this is confirm that the schema is in fact connected and both the queryFields and dataFields are fully selected. In my case, somehow only the queryFields were selected, which let's the form pull data, but the dataFields also need to be selected to push data, which is why on the new item form I wasn't able to type in the text boxes.
So, as can be seen in the screen shot below, simply go to the Data tab, and under Default Values, ensure that the entire tree of fields are fully selected:
