Ok I know what its happening and this is a huge issue that I need to figure out how to solve. You are using cPanel 11 and I developed the patch for cPanel 10.
Both versions have different ways to change the password of the IMAP accounts. cPanel 11 doesn't have the dowebmailpasswd.cgi script, so I'll have to make a different version of the patch for cPanel 11.
I am on it right now, so you can expect this release maybe today or tomorrow. Thanks for your report, it helps improving the eficience of the patch.
Please stay in touch with the forum so you can be notified when the new release comes out.