PrincipalContext pc1 = new PrincipalContext(ContextType.Domain, "DomainName", UserAccountOU, UserName, Password);
UserPrincipal UserPrincipalID = UserPrincipal.FindByIdentity(pc1, IdentityType.SamAccountName, UserID);
searcher.Filter = "(&(ObjectClass=group)(member = " + UserPrincipalID.DistinguishedName + "));