Putting a datatable into a dataset problem

[Elfish]

I am trying to put a datatable into a dateset, which I then export to a CSV file. I am getting this error

DataTable already belongs to another DataSet. on the following line dsExport.Tables.Add(dtExport)

Using dtExport As DataTable = DirectCast(dgvSafetyGlasses.DataSource, DataTable)
            Using dsExport As New DataSet()
                dsExport.Tables.Add(dtExport)
                ExportDatasetToCsv(dsExport)
            End Using
        End Using

What am I doing wrong?