Lookup with multiple values

Hiya

I've put a few fields in a table which are looking up values in another table, and I ticked the multiple items box in the wizard.

This works fine if I want to enter data into the table, I get a nice little dropdown tick box. But I've also made a form to make data entry easier and these particular fields have an empty dropdown box in the form.

Is there something else I have to do to the format of the field or the form so that the form is seeing the lookup data?

Thanks,

Debbie