Can't select a shape to assign it a layer

[Joshua Campbell]

I've imported a CAD drawing into Visio. I've gone through and assigned
everything a layer. To make sure that I got everything, I went to the
Layers widow and unchecked Visible on all the items. However, there are
still shapes and so forth on the drawing. The really bad part is that I can
not select the shapes. Even if I go to Edit -> Select All, nothing gets
selected. Does anyone have any ideas on what I can do to access these
shapes?

Thanks.