Access 2003 combo box not working properly

Access 2003 NEWBIE. I have a DB with 5 tables. I have 5 forms as well. On my main form I have a few comboboxes that pull values from a table, and they work great. I just added a new combobox to this form using the wizard, it asked me what table to get values from, I told it tblStudentName, and I told it to use StudentName field in said table. Now I open the form and I drop down this Student name field and sure enough all the names in the table show up. So far so good, but I notice when I go into design view it sayd the field is UNBOUND. So I go into the prop for that field, and in the control source dropdown I do not see the field StudentName showing up to pick. Row Source Type says Table/Query, and the Row Source says tblStudentName. But when I drop down Control Source, StudentName is not a choice. The reason I need to fix this is I have an ADD RECORD button that clears the form and allows a new record to be fiilled in, and this Student Name field never clears, and I assume its because its UNBOUND. Its almost like the field prop doesn't see the tblStudentName despite me telling it that is the table to use.
thx experts...BobR