Specified cast is not valid

Question

Trying to call a legacy VB6 control and get the following error at runtime. Code compiles clean. An unhandled exception of type 'System.InvalidCastException' occurred in TestPredict.exe Additional information: Specified cast is not valid. Code ---> VB6 Active X Public Function GetConcentration(ByRef Values As Variant, ByRef Size As Long) Dim tValues() As Double If fPredict = True Then Size = dGetItemSize(hCal, "concentration") If Size = 0 Then GetConcentration = -3 'if value not available Else ReDim tValues(1 To Size) GetConcentration = dCopyItem(hCal, tValues(1), "concentration", Size) GetConcentration = 0 'success Values = tValues End If Else GetConcentration = -2 'if prediction not available End If End Function C# call ---> object fValues = new double(); err = IQPredict.GetConcforCSharp(ref fValues, ref size); errlabel.Text = Convert.ToString(err); double[] fval = new double[size]; fval[0] = ((double[])fValues)[0];