could not find installable ISAM

try
{
     string str = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=FromTrn.mdb;UID =admin;PWD =sisvb;";
     OleDbConnection AccConn = new OleDbConnection(str);
     AccConn.Open();
}
catch (Exception Er) 
{ 
     MessageBox.Show( Er.Message.ToString()); 
}