Not a solution, but you might do some detective work: The error message says "Library not loaded: libmysqlclient.18.dylib". So you could execute the following on the command line and see whether a) the file does not exit, b) the file exists but not where the script expects it or c) a different version of that file exists, for example libmysqlclient.19.dylib

find / -name 'libmysqlclient*' -print
[download]

Probably you can do the same with sherlock or whatever its called in the gui

A look at line 17 (and preceding lines) of ptest.pl might also give some hints