Have run into another problem - hoping for any guidance on this one:

After completing the following steps...
1.) Open new file, set size
2.) Load releif from previous file
3.) Pasting change size 3D clipart, apply, center drawing, paste and close.
4.) Save new art cam and relief files w/new file name
5.) Check 3D view, new dimensions
6.) Follow steps of machining in toolpaths
7.) Type in .25 machine safe Z in top and bottom boxes
8. Do material setup and...

this is where I have a problem...when the "model position in material" screen appears, the okay command is not highlighted and I can't adjust the three lower boxes. I can make changes to the "top offset/bottom offset" and material thickness commands. So, I hit cancel and try again. I think the second time I tried, the number in the middle of the three lower boxes changed to a larger figure. What is going on? thanks!