Dymola Simple model: Pumping out air from volume not working

Question

during some Dymola exercises, I like to pump some fluid out of a closed volume. The model looks quite simple:

Unfortunatelly, I always get the "Simulation failed for:" message.. The medium is always the same (Modelica.Media.Air.MoistAir).

Here is the code:

model pump_out_example
    
  Modelica.Fluid.Machines.ControlledPump pump(
    use_m_flow_set=true,
    redeclare package Medium = Modelica.Media.Air.MoistAir,
    allowFlowReversal=false,
    control_m_flow=true,
    nParallel=1,
    use_T_start=true,
    m_flow_nominal=1.5,
    T_start=293.15,
    p_a_nominal=102200,
    p_b_nominal=102400)
    annotation (Placement(transformation(extent={{-14,-22},{-34,-2}})));
  Modelica.Fluid.Sources.FixedBoundary ambient_air(
    use_T=true,
    redeclare package Medium = Modelica.Media.Air.MoistAir,
    p=system.p_ambient,
    T=system.T_ambient,
    nPorts=1)
    annotation (Placement(transformation(extent={{-72,-22},{-52,-2}})));
  Modelica.Blocks.Sources.RealExpression kg_s(y=0.1)
    annotation (Placement(transformation(extent={{0,-2},{-12,20}})));
  inner Modelica.Fluid.System system(
    energyDynamics=Modelica.Fluid.Types.Dynamics.FixedInitial,
    m_flow_start=0,
    allowFlowReversal=false,
    T_ambient=283.15)
    annotation (Placement(transformation(extent={{-90,10},{-70,30}})));
  Modelica.Fluid.Vessels.ClosedVolume Fixvolume(
    V=50,
    nPorts=1,
    redeclare package Medium = Modelica.Media.Air.MoistAir,
    use_T_start=true,
    use_portsData=false,
    T_start=293.15)
    annotation (Placement(transformation(extent={{10,-2},{30,18}})));
equation 
  connect(pump.port_b, ambient_air.ports[1])
    annotation (Line(points={{-34,-12},{-52,-12}}, color={0,127,255}));
  connect(kg_s.y, pump.m_flow_set)
    annotation (Line(points={{-12.6,9},{-19,9},{-19,-3.8}}, color={0,0,127}));
  connect(pump.port_a, Fixvolume.ports[1])
    annotation (Line(points={{-14,-12},{20,-12},{20,-2}}, color={0,127,255}));
  annotation (
    uses(Modelica(version="3.2.2")),
    Diagram(coordinateSystem(extent={{-100,-40},{60,80}})),
    Icon(coordinateSystem(extent={{-100,-40},{60,80}})));
end pump_out_example;