diff --git a/matlab/AddLumpedPort.m b/matlab/AddLumpedPort.m
index d14aa63..0aa65f6 100644
--- a/matlab/AddLumpedPort.m
+++ b/matlab/AddLumpedPort.m
@@ -53,11 +53,14 @@ end
 if (R>0)
     CSX = AddLumpedElement(CSX,['port_resist_' int2str(portnr)],  n_dir-1, 'Caps', 1, 'R', R);
     CSX = AddBox(CSX,['port_resist_' int2str(portnr)], prio, start, stop);
+else
+    CSX = AddMetal(CSX,['port_resist_' int2str(portnr)]);
+    CSX = AddBox(CSX,['port_resist_' int2str(portnr)], prio, start, stop);
 end
 
 % create excitation
 if (nargin >= 8) && ~isempty(excitename)
-    CSX = AddExcitation( CSX, excitename, R<=0, -dir*direction, varargin{:});
+    CSX = AddExcitation( CSX, excitename, 0, -dir*direction, varargin{:});
 	CSX = AddBox( CSX, excitename, prio, start, stop );
 end