I have just found out what the problem was. For some reason, if you have the form's ScrollBars property set to 3 - Both the DateTime picker won't activate. As soon as I changed this setting to 0 - None, the control operates normally. I have no idea why this would have any influence on an ActiveX control. I've been working with FoxPro since before FoxPro- since dBase III+ - and I'm sometimes still amazed at the odd bits and weirdness in the system.