No Default SQL Instance On Install?

Problem: When the application installs it requires SQL Express
Server 2005. If it does not exist it will install it or
rollback. -> continue installation -> When the form
attempts to locate an SQL Instance on a machine that has not had SQL
server or any components connected before it shows up as
<null>. I need to have access to the server(s) instances in
order to build the application database inside SQL. Am I using
the wrong approach with SQLDMO? Is there adifferent method
to access the installed SQL Express 2005 connection string?

Current code to locate SQL Instances:

try
{


////////////////////////////////////////


// Search and List SQL Server Instances


////////////////////////////////////////

//set cursor to thinking/hourglass


System.Windows.Forms.Cursor.Current =
System.Windows.Forms.Cursors.AppStarting;

//begin


ArrayList aServers = new ArrayList();


SQLDMO.ApplicationClass acServers = new SQLDMO.ApplicationClass();
//loop through the servers found


for (int iServerGroupCount = 1; iServerGroupCount <=
acServers.ServerGroups.Count; iServerGroupCount++)
{


for (int iServerCount = 1; iServerCount <=
acServers.ServerGroups.Item(iServerGroupCount).RegisteredServers.Count;
iServerCount++)
{


aServers.Add(acServers.ServerGroups.Item(iServerGroupCount).RegisteredServers.Item(iServerCount).Name);
}
}


//add the servers to the drop down box
if (aServers.Count < 1)
{


string NotExist = "<No Servers Found>";


cboServers.Items.Add(NotExist);



cboServers.SelectedIndex = 0;


btnSQLDataBaseCheckDB.Enabled = false;

}
else
{


cboServers.Items.AddRange(aServers.ToArray());


//select the first item in the array index to display


cboServers.SelectedIndex = 0;
}
}
catch (Exception ServerException)
{


MessageBox.Show(ServerException.Message);
}





Slightly stuck at the moment with this. Any tips or leads in the right direction would be greatly appreciated.