problems PAR, MailBox and Active Perl

Hello,

I tried to use ActivePerl with the PAR package to get a standalone binary
for windows.
Unfortunately I ran into problems. I use

- ActivePerl 5.8.3.809-MSWin32-x86
- Mail-Box 2.053
- PAR 0.75

I'm able to generate simple tools with PAR without problems so I assume
basic setup is
correct. When I try to use Mail-Box package inside a PAR binary I get an
error message:

Can't locate Mail/Message/Construct/Read.pm in @INC (@INC contains:
CODE(0xd2db34) .) at (eval 36) line 3, <HANDLE> line 54.

The code Mail/Message/Construct/Read.pm isn't included in the PAR but I
don't recognize why.

Any hints?
Did anybody use PAR on windows in combination with Mail-Box package?

Regards
    Markus