Getting Outputs with API

Hello everyone.

I made the following function in VBA (Excel) to retrieve the value of the variable B from the mathcad file using the API.

The Variable is defined in the file with a unit i.e. B := 2 m

Public Function test2() As Double

    Dim objApp As Ptc_MathcadPrime_Automation.Application

    Set objApp = New Ptc_MathcadPrime_Automation.Application

    Dim b As Ptc_MathcadPrime_Automation.WorksheetReadonlyOptions

    Set b = objApp.CreateWorksheetReadonlyOptions

    bb = b.SetOptionValue(WorksheetReadonlyOptionNames_RequestToUpdateInputsEnabled, 2)

    Dim objCalc As Ptc_MathcadPrime_Automation.IMathcadPrimeWorksheet3

    Set objCalc = objApp.OpenEx("C:\Users\kai.jakob\Desktop\Testo.mcdx", b)

    Dim a As Ptc_MathcadPrime_Automation.IMathcadPrimeOutputResult

    Set a = objCalc.OutputGetRealValue("(@LABEL VARIABLE B)")

    Set a = objCalc.OutputGetRealValue("B")

    aa = a.RealResult

    aaa = a.Units

    test2 = aa

    objCalc.Close (SaveOption_spSaveChanges)

    objApp.Quit (SaveOption_spDiscardChanges) 

End Function

The output I get is:

Double:      aa = -1.#IND

Unit:          aaa = ""

Can anyone tell me what is wrong with those functions?