TextHolder on stage showing up as Placeholder...can not be casted?

I have a textbox on the 3rd slide of my presentation. This textbox is not on the Master Slide, it is specific to this slide. It comes up as an Aspose.Powerpoint.Placeholder with PlaceholderType = PlaceholderType.Body. When I try to cast this as a TextHolder…it errors out saying it was an invalid cast. I am performing the cast like this:

TextHolder th = (TextHolder)pl;

where pl is the placeholder object. Any ideas why this won’t work?

Dear Michael,

So placeholder was not recognized as textholder.
I should have real ppt to tell exactly why it happened.

Possible reason is PowerPoint wrote text of placeholder to the linked textframe.