Sorry, found the answer its not "DataSource" but "Data Source".

I'm also having a problem with the names of the colums in the excel sheet, I'm referring to them as "A" and "B" and so on. But that doesnt seem to work. Keeps telling me there is no datacolumn by the name of "B" or "H", I think I'm just getting the column names wrong?

OleDbConnection myConn = new OleDbConnection(Conn);
OleDbCommand myComm = new OleDbCommand("select * from [Sheet1$]",myConn);
OleDbDataAdapter adapt = new OleDbDataAdapter();
adapt.SelectCommand = myComm;
DataSet ds = new DataSet();
myConn.Open();
adapt.Fill(ds);
myConn.Close();
DataView dv = new DataView(ds.Tables[0]);
foreach (DataRowView drv in dv)
{			MessageBox.Show(drv["B"].ToString().Trim()+drv["H"].ToString().Trim()+drv["I"].ToString().Trim());
}