C# ambiguous call DataColumnCollection.Add(System.Data.DataColumn)' and 'System.Data.DataColumnCollection.Add(string)
<p>below is the code i'm using and i've used this 100x's before.  And now it's throwing an error, basically i'm trying to dynamically create the Columns based on the first row of an excel file.  The error that i'm receiving now is:</p>

<p><code>The call is ambiguous between the following methods or properties: 'System.Data.DataColumnCollection.Add(System.Data.DataColumn)' and 'System.Data.DataColumnCollection.Add(string)'</code></p>

<pre><code>DataTable excel_Holding_Table = new DataTable();
        DataRow row;
        Microsoft.Office.Interop.Excel.Range range = workSheet.UsedRange;
        for (int i = 1; i &lt;= range.Columns.Count; i++)
        {
            excel_Holding_Table.Columns.Add(Convert.ToString(((Microsoft.Office.Interop.Excel.Range)workSheet.Cells[1, i]).Value2));
        }
</code></pre>

<p>What do I need to do to prevent this from happening, this has never appeared.</p>

<p>here is my using:</p>

<pre>using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.IO;
</pre>
