relationship issue

[badangel]

Hi, I've have a relationship issue I think. I have a primary key on a customer table which is an autonumber with a lettered prefix. I would like the contents of this column to appear in a combo box in an equipment form but i am not able to do this for some reason. What data type should the combo box be coz when I try to change it to anything other than autonumber it causes an error but if its autonumber then it creates a number thats not in the original table?

Thanks in advance. Sorry if this is a really dumb question!