First, you could use an Action Button.
Did you make your command button using the Control Toolbox?
Also, go into VBA and check your references (Tools - References) and see if you have the lastest version (in order) Visual Basic for Applications, Microsoft PowerPoint 9.0 Object Lib, Ole Automation, Microsoft Office 9.0 Object lib, and Microsoft Forms 2.0 Object lib. If a library is missing, some of the ActiveX controls don't work.