Web API consuming Icollection conversion error

I got a project which consume a web api in asp.net mvc I got two table Client and Compte and between them i got a bridge table in my app i have to show the list of Compte (account ) associated to a specific Client

this is the problem that i got http://localhost:50685/Comptes/AfficherComptes/System.Collections.Generic.HashSet%601[ConsumingWebAPI.Models.Compte]