An issue with parameters and and initial equations

[ceraolo]

In the following model I get always varPar=pi/2, whatever value I give Ipm.

model Test2 
  import Modelica.Constants.pi;
  parameter Real Ipm = 1.5;
  parameter Real varPar (fixed=false);
initial equation
  if Ipm>1.0 then
    varPar=pi/2;
  else
    varPar=asin(Ipm);
  end if;
equation
end Test2;