This may be due to the security restrictions set for the PowerPoint add-ins. Please change the settings as mentioned below:
PowerPoint 2002, PowerPoint 2003
- Go to Tools -> Macro -> Security;
- Select the Trusted Publishers tab on the Security widow;
- Check the box next to Trust all installed add-ins and templates.
- Click OK and restart PowerPoint.
- Click on the Office button (the round button with Office logo on the top left corner of the PowerPoint application window).
- Click the button 'PowerPoint Options' at the bottom of the window.
- Click the command 'Trust Center' on the left window pane.
- Click the button 'Trust Center Settings
- Choose the command 'Macro Settings' on the left window pane.
- In the section, 'Developer Macro Settings', check on 'Trust access to the VBA project object model'.
- Click OK and again OK.