When you have an error in Zimbra please check all the
log files (including installation logs) and post the full error messages you see, also post details of whether this is a new install or an upgrade and which version and release of Zimbra you're using. It would also help if you searched the forums for similar problems and tried some of the suggestions, the likelihood is that your problem has been seen before and has a resolution.
Having said all that search the forums for 'requiretty', I'd hazard a guess that might solve your problem.