The trick is to create a new "Build-Specification".
Default is exe, then only right-click on "Build-Specifications" ad select "New + Shared Library (DLL)". Then a DLL is created.
Works now without problems.
One more question is:
When i create a function with "typical" types like string or numeric then TestStand says "This function has parameter information. Would you like to use it?". When i click "YES" the the parameters are automatically added in the teststand-steptype.
But when i add the default labview-errorcluster as an output and do the same then TestStand says: "this function does not have parameter information in the DLL or types not recogniced by Teststand."
Is there a trick that the error-output can be automatically added?
In the project-explorer in "Define Prototype" the function-call looks like this:
void SumTest(double NrA, double NrB, double *Sum, double *Mal, TD1 *errorOut)