For users of the Perl modules XML::LibXML and XML::LibXSLT, you will save yourself much puzzlement if you understand that “Can't coerce GLOB to string in entersub” really means “file not found.”
NOTE that the file which is not found might be your XML, your XSLT, or the schema / DTD for these things! Maybe some -e tests are in order (but don't forget that filenames hidden in your XML pointing to bad DTD paths, for example, will throw the same cryptic error).
See also http://maclux-rz.uibk.ac.at/~maillists/axkit-users/msg05794.shtml