Plaban
Since Roles at the Role-Owner stage requires an Approver to route to next stage and out of 2 Roles as mentioned by you earlier ,1 Role don't have a Approver it automatically chooses the Escape Route.So MSMP doesn't determine path for 1 Role only since both the roles are part of the same request.
Therefore either both the roles should have Role Owners defined or both can have them missing .
Try removing the role with no role owners and it should work.
Please let us know how it went .
Regards
Pradeep