Unable to login on the portal by using second domain

Hello team

We have Forefront Identity Access Gateway 2010 with SP3 (Version- 4.0.3206.10100). We create a portal link with https trunk and able to access SharePoint sites with first domain- User login details are as below-

user

password

domain

And able to access all the SharePoint sites which are published on the portal. But when we are trying to login on the portal by using second accepted domain its failed and says Authentication failed- 

[We have a 1-way trust between forests.  domain1 trusts domain2; but domain2 does NOT trust Domain1. ]

Whereas we already added both domain name in authentication option.

Please help me-

Thanks Ranveer Katiyar