Cause:

Solution:

1) If the Database window is not activated, activate the Database window.
2) Click the 'Forms' tab in the Database window.
Forms tab
3) Select the desired form from the list box. (The selected form is highlighted.)
4) Click 'Design'. (The selected form appears in the From Design view.
5) Click to select the desired control to format. (Handles appear around the control.)
Handles appear around control
6) Select the 'View' menu and select 'Properties'. (The property sheet appears.)
Property Sheet
7) Click the 'Data' tab.
8) Click in the 'Locked' property box. (A down arrow appears.)
Click Data tab, select Locked property box
9) Click on the down arrow. (A drop-down list appears.)
10) Select 'No'. (The control is un-locked.)
11) To close the property sheet, click the 'X' in the upper-right hand corner of the property sheet.
Click X button to close property sheet