Hello, thanks for your interest in SAMSON! Could you please log in to SAMSON Connect and go to My SAMSON / My Elements to check that you have not removed the Basic importers SAMSON Element that should be added by default? If necessary, here is the link to add it again: https://www.samson-connect.net/element/385fe362-adfd-ce55-95c0-4e63560efa29.html.
(I renamed the file you provided to methane.pdb and it worked here.)
Best,
Stephane