Vopmail and courier authenication

[adureli]

I'm using qmail/vpopmail/courier as my mail server. I can login from mail clients and from squirremail (webmail). But I cant login in roundcube. In the logs i can see: "Authentication for xxx@xxx failed (LOGIN): "a001 NO Login failed." I think the problem may be the authvchkw module in courier, which I use to authenticate.
Can anyone help?