chdir "": No such file or directory

hi all, 
       In my sqwebmail using ldap authendication,
once I login with valid user name and password,
I am getting 

Server error!
 Error message:
Premature end of script headers: sqwebmail 
   
in the log,
 chdir "": No such file or directory

I tried changing 

LDAP_HOMEDIR           homeDirectory
LDAP_MAILROOT        /var/vmail

in authldaprc file, but still the same error,
need your help to solve this issue!

Thanks,
-bala-

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