The purchaser can enter a bid or RFx response on behalf of a bidder. For example, if you as bidder are not able to access the system, you can contact the purchaser to enter a bid or RFx response as your substitute.
To bid as substitute, the purchaser must have authorization for transaction BBP_QUOT_BOB. The first authorization level enables the purchaser to create new bids; the second authorization level enables the purchaser to change submitted bids, as well as create new bids.
Surrogate Bidding is possible from SAP SRM 5.0, The screenshot attached is from SAP SRM Enhancement pack 2.
Please ensure that the bidder is permitted for surrogate bidding,. You can do so by creating a RFx and Publishing it. Open Rewards and Response screen,Lead Select a bidder , the "Response On Behalf" link is not enabled.
The one of the reason can be missing authorization to bidder profile.
This can be achieved by using below Steps.
1) Open the Business Partner POWL and search for the BIDDER