modules not found

Am not shure if this is more of a general problem. I installed perl
into an unusual directory but new modules, like XML-Parser, weren't
able to find installed modules, like ExtUtils. Though the @INC output in
the error message was fully correct. I installed perl into /usr and it
just worked for so. 

Can somebody give me a hint if there's some general problem with perl
when not resided in /usr

Regards,
Dennis Heuer