Running EMCA Fails To Accept the DBSNMP Password

Today when I tried to create DB Control on my computer I got an interesting problem.

Problem Description:

oracle@neptune:/$ emca -config dbcontrol db -repos recreate

STARTED EMCA at Apr 15, 2008 11:05:06 AM
EM Configuration Assistant, Version 10.2.0.1.0 Production
Copyright (c) 2003, 2005, Oracle. All rights reserved.

Enter the following information:
Database SID: ARJU
Listener port number: 1521
Password for SYS user:
Password for DBSNMP user: ------Here I have given a
Invalid username/password.
Password for DBSNMP user:
Invalid username/password.

It continues to invoke password until I press ctrl+C.
Though I was giving correct password it does not accept DBSNMP password. I got tried, I search through google but did not get any clue. Even to be more sure I have changed DBNMP password though database and then tried but no result , the problem continues.

Then what I did is I have given password inside "" Double quotes and that worked. :)

oracle@neptune:/$ emca -config dbcontrol db -repos recreate

STARTED EMCA at Apr 15, 2008 11:10:29 AM
EM Configuration Assistant, Version 10.2.0.1.0 Production
Copyright (c) 2003, 2005, Oracle. All rights reserved.

Enter the following information:
Database SID: arju
Listener port number: 1521
Password for SYS user:
Password for DBSNMP user: ----Here I have given "A" or "a" Both worked.
Password for SYSMAN user:
Email address for notifications (optional):
Outgoing Mail (SMTP) server for notifications (optional):
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