connecting to sql express 2005 with C#

Hi,

I've my win32 application which connecting to my sql database.
till now i used MSDE as my database and now i want to upgrade to sql express
2005. after the upgrade i tried to connect to the database and couldn't. i
keep getting an error which saying that database doesn't exists or access is
denied.
is there something diffrent between connecting to MSDE and connecting to sql
express 2005 ? here with my connection string.

sqlConnStr=@"data source="+192.165.1.1+";initial catalog=master;user
id="+sa+";password="+1234+";workstation id=127.0.0.1;packet size=4096";

Thanks,
Gidi.