MultivariateTDistribution::vrprm:
   The value {Indeterminate, Indeterminate, Indeterminate, Indeterminate,
     Indeterminate, Indeterminate} at position 1 in
    MultivariateTDistribution[{Indeterminate, Indeterminate, Indeterminate,
      Indeterminate, Indeterminate, Indeterminate},
     {{0.1, 0., 0., 0., 0., 0.}, <<4>>, {0., 0., 0., <<2>>, 0.1}}, 3] is
     expected to be a list of real numbers.

drawDensity[mean_, s2_] := Module[{},

  scaleMatrixEcon = IdentityMatrix[6];

  If[Select[mean, Element[#, Reals] &] != mean,
   mean2 = theta; (*theta is a list of global parameters*)
   ,
   mean2 = mean;
   ];
  RandomVariate[
   MultivariateTDistribution[mean2, s2*scaleMatrixEcon, 3]]
  ]