In order to process the transaction, the tribute information needs to be linked to the appropriate record in The Raiser's Edge. 

Follow the steps here to link Tributes

Note: It is a known issue that the binoculars icon to search for the tribute will remain grayed out even when creating a new tribute if all needed requirements are not set in both RE and BBNC. The transaction may need to be entered manually into The Raiser's Edge and then deleted in NetCommunity. 

The NetCommunity donation form part must have the need tribute type boxes marked for the tribute to link. If the needed tribute types are not marked as seen below please edit the donation form part. 
User-added image

If you recently enabled the Tribute module in Raiser's Edge, but did not yet create any Tribute Types. The new Raiser's Edge module addition will auto-enable the feature on all NetCommunity donation forms, we suggest to add tribute types in Raiser's Edge or disable tributes in NetCommunity to resolve the issue for future gifts.