Fetchmail not working and putting errors in maillog

Hi,

I hope that I someone can help me. I am trying to use fetchmail with 
fetchmail.pl. I am running as the vmail user and this is the errors I 
see in my mail log:

fetchmail-all[19497]: fetch [email protected] for [email protected]
fetchmail[19498]: 9955 messages for [email protected] at pop.mail.yahoo.com 
(1982615899 octets).
fetchmail[19498]: reading message 
[email protected]@any-jpop.mail.gm0.yahoodns.net:1 of 9955 (34082 octets) 
(log message incomplete)
fetchmail[19498]: Cannot switch effective user id to 2001: Operation not 
permitted
fetchmail[19498]: MDA error while fetching from 
[email protected]@pop.mail.yahoo.com
fetchmail[19498]: Query status=6 (IOERR)

I have tried to find a solution, but I am unable to solve this error. 
Dovecot does deliver email that are received from postfix after I added 
virtualmail to the dovecot group.

Please let me know if other information is needed.

Kind Regards,
Al