OAM Authentication issue for webgate 10g and 11g.

Scenario:

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grp.abc.com resource is in webgate 11g configuration.

webgate 10g has .abc.com set as primary cookie domain.

Working case:

1.Login to grp.abc.com with valid credentials. (protected by 10g webgate)

2.After logging in successfully click on link grp.abc.com/sample which is protected by 10g webgate

3. It is automatically redirected with out any futher authentication.

Non Working case:

1.Login to grp.abc.com  with valid credentials. (protected by 11g webgate)

2.After logging in successfully click on grp.abc.com/sample (protected by 10g webgate)

3.Another authentication page pops up where we have to submit credentials again and then we are redirected the page