[RESOLVED] Datatable - creating new columns ignores datatype?

[happyme]

I have a datatable which has a number of rows containing data

Then I need to add some empty datacolumns which I do like this:

   
Dim OT_Hours As New DataColumn("OT_Hours")
OT_Hours.DataType = System.Type.GetType("System.Double")
OT_Hours.DefaultValue = 0
MyTable.Columns.Add("OT_Hours")

When I come to use the datatable I find that these new columns now have datatype String and initial values of ""

I tested this using:

For Each column As DataColumn In MyTable.Columns

  Console.WriteLine(column.ColumnName & " is a " & Type.GetTypeCode(column.DataType).ToString) 

Next

I need to use these columns for calculations

any ideas?

What am I doing wrong?