For user name, one cannot just enter “a1234567”, TDP is not same as Toad for Hadoop, it needs to use the FULL name as in the KDC server, so, one must confirm the full user name with their Kerberos admin, it should be something like below:
Userid/host@realm (for example , a1234567@sub_subbdomain.subbdomain.domain.COM )