[ms office - 2010] Infopath rule to set value from another field

[HMCTech]

I have a form in infopath that has one field which is a drop down of values. I need that value to be also entered in another text box. I have made a rule that sets that field value but instead of the text from the drop down it just inputs the ID. Is there another,easier way to accomplish this?

[AngryTechnician]

How is the dropdown list populated? Using a datasource or manually entered?

[HMCTech]

Using a datasource

[HMCTech]

Did not fix this, but went for a combo box instead of a drop down.