Infopath 2010 "Get choices from fields in this form" combo box is read only. Why?

Question

I created an Infopath custom form and I want to have a combo box that retrieves its data from other fields in the form (user fills a repeating group in View 1 and then in View 2 I want to display the inserted items in a combo so that user makes a selection and go to View 3.

In the Data tab of the combo box control I've set up the "Get choices from fields in this form" option and specified the group.

When View 2 is shown I see the combo but it is readonly. I can't for the life of me figure out why. Even if I change the control to something else, like a List, it is still readonly.

The values are all there (I see that in the source) but the combo is readonly/disabled.

Have you encountered this? Is there something else I need to do? Am I missing something?

EDIT: I just created a receive data connection of type XML, with some options inside, set this as the values for the combo. I again see the values in the source code but the combo is still disabled/readonly. What could be the cause?

Answer 1

Managed to figure it out!

The list of values I was going after did not have an empty element inside, while the field I was setting the "Get choices from fields in this form" option had an empty value.

You can add an empty element in the source list or set the target field to have a default value to something in the source list.