What i am doing wrong?

This is a code to populate a combobox.

Utilitarios oUtil=new Utilitarios();
sqlquery="Select * from area_caja order by descripcion";
cboarea.DataSource= oUtil.CreateDataSet(sqlquery);
cboarea.DisplayMember = "descripcion";

where CreateDateSet is:

public DataSet CreateDataSet(string sqlstring)
{
Utilitarios oUtil=new Utilitarios();
cn.ConnectionString = oUtil.GetConnectionstring();
OleDbCommand Cmd = new OleDbCommand (sqlstring, cn);
OleDbDataAdapter da = new OleDbDataAdapter(Cmd);
DataSet ds = new DataSet();
da.Fill(ds);
cn.Close();
return ds;
}

The problem is that the text displayed on the combo is:
System.Data.....