Password incorrect

Hi, I have a strange problem with QPopper 4.0.16 on Fedora Core 10.
I have installed QPopper with this option:

./configure --enable-standalone --without-pam

I have created users called 'test' but when I try to check mail I have 
always in log file:

Mar 24 12:27:27 localhost popper[6488]: test at 192.168.1.15 
(192.168.1.15): -ERR [AUTH] Password supplied for "test" is incorrect.
Mar 24 12:27:27 localhost popper[6488]: [AUTH] Failed attempted login to 
test from host (192.168.1.15) 192.168.1.15

..but the password is certainly correct (for example with openwebmail I 
haven't problem) !
Thanks in advance.

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   Salvatore.