Access: Building data access page

I have build a Access database. I have a table name called customers. I have created a data access page for my office to use to enter the data. When I open that data access page and try to add a record it says "You can't add a new record or delete an exciting record because the recordset for this page is read-only". I have looked every where to fine where this page is set to read-only. What can I do. Thanks for your time.