Clipping mask / Text on path

I have created a circle using the Ellipse Tool and placed text around that circle using Type on a Path tool. I have placed a TIFF image in to Illustrator in the hope of creating a clipping mask with the circle (with text) so the image shows within the circle. I can do this when I haven't used Type on a Path but Illuustrator won't allow me to do so with the text in place.

Can anyone help?