Ansys staff can not upload/download any files on the forum, so if you want to reach a larger audience to get answers from, please insert inline images describing your problem.
What analysis are you doing? Regardless, you can't simply import stl as is in mechanical, as you would need some preprocessing done on it.
Search for Editing STL with ANSYS SpaceClaim
and you will see some good video tutorials.
-Aniket
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