[VB.NET] [MWArray] Can't cast MWNumericArray to MWCellArray

I'm currently working on a project to reroute an existing .NET tool from an 'old' DLL-deploy to the .NET DLL-deploy. So far, so good. I am calling the DLL and it initializes. However, it seems you need to feed the newer DLL-type with the MWArray data-types. I am using a 2011a DLL in 32-bits.

So I switched from the old 'Object-type' to designated MWArrays. I have 5 arrays, 4 of which are exclusively numeric in the data it needs to hold. The fifth, has a small problem, because it will have to contain string-types and numerics (doubles). For this, I have read I need to use the MWCellArray, but it does not work, and I keep getting the following error message;

Unable to cast object of type 'MathWorks.MATLAB.NET.Arrays.MWNumericArray' to type 'MathWorks.MATLAB.NET.Arrays.MWCellArray

This is the calling code;

Dim dr As DataRow

              For rowIndex As Integer = 0 To dTable.Rows.Count - 1

                  dr = dTable.Rows(rowIndex)
                  newArray(rowIndex, 0) = CDbl(dr(0))

                   For columnIndex As Integer = startkolom + 1 To  dTable.Columns.Count - 1

                      If dr(columnIndex) Is Nothing OrElse _
                          IsDBNull(dr(columnIndex)) OrElse _
                          dr(columnIndex).ToString.Length = 0 OrElse _
                          dr(columnIndex).ToString = "#N/A" Then

                          newArray(rowIndex, columnIndex - startkolom) = Double.NaN
                      Else
                          If IsNumeric(dr(columnIndex)) Then

                              newArray(rowIndex, columnIndex - startkolom) = CDbl(dr(columnIndex))
                          Else
                              newArray(rowIndex, columnIndex - startkolom) = dr(columnIndex)
                          End If
                      End If
                  Next
              Next