Drop down buttons don't appear in a new form

[franck]

I have 3 tables linked to each other called Cars, Type and Make. When I create an autoform columnar on the Cars table I do not get the drop down button for the Type and Make fields. The buttons are there on the datasheet view of the cars table but not on the new form. I am then forced into deleting the offending fields from the form and then reinserting them where they always appear with the drop downs.

Do you know why and more importantly can you help resolve this for me.

Regards Franck