Hi,
I am a new user but  as i know ( and it work well)  you have to write in the text .

For example  if you use an opentank :

package Medium = Modelica.Media.Water.StandardWaterOnePhase;
Modelica.Fluid.Vessels.OpenTank tank1(redeclare package Medium = Medium, ...)


you have to do this for every object you use in a fluid model.

Hey,

Thanks for your answer.
I have already tried it that way but there is a good chance that i made a mistake ( my first modelica).
So i will try again:)