Update involving a list field

Hi, Im using a form that updates a database entry. In it one of my fields is a drop down/list field. Whenever the value in this field is changed, instead of updating it to the new item, it is deleted entirely. I have the same field in my entry page that inserts just fine, but for some reason the update deletes the info. Is there something special about updating a recordset off of a dropdown field that I am missing? if it matters, im pulling the initial value of the field from the value in the database row.I can send the code for the page to anyone who needs more info. Shiloh