workflow - trying to use econnect in crm as a plugin but could not load assembly -

so have decided go econnect communicate crm gp , trying implement econnect in crm plugin. issue when calling plugin fails , error im not sure how crm see microsoft.dynamics.gp.econnect dll. tried registering gac , disc (as db) plugin registration tool wouldn't let me. appreciated

error depicted in image is: "error occurred in execute method: not load file or assembly 'microsoft.dynamics.gp.econnect, version 12.0.0.0, culture=neutral, publickeytoken=31bf3856ad364e35' or 1 of dependencies. system cannot find file specified.