This issue occurs if the database is not trusted by Access 2007. By default, Access 2007 opens databases that are not trusted in Disabled mode. In Disabled mode, executable content is disabled.

If you trust the author of the Access 2007 database, and if you want to enable the database, use one of the following methods.
Method 1: Enable the database for the current session
When you use this method, Access 2007 enables the database until you close the database. To enable the database for the current session, follow these steps:

    On the Message Bar, click Options.
    In the Microsoft Office Security Options dialog box, click Enable this content, and then click OK.

Note You must repeat these steps every time that you open the database.
Method 2: Move the database to a trusted location
To do this, follow these steps:

    Determine trusted locations to which you can move the database. To do this, follow these steps:
        Click the Microsoft Office Button, and then click Access Options.
        Click Trust Center, and then click Trust Center Settings under Microsoft Office Access Trust Center.
        Click Trusted Locations, and then use one of the following procedures:
            Note the paths of the trusted locations that are listed.
            Add a new trusted location. To do this, click Add new location, and then specify the path of the location that you want to add.
    Move the Access 2007 database to the trusted location that you want.