Connect problem with sql server r2 Express

Dear guys
I got problem with sql server r2 express.  We have a software use conntection string as :

Cn.ConnectionString =
"Data Source=.;Initial Catalog=Fbc_Soft;User ID=FBC;Password=Friends@123"

We working with Sql Server R2 no problem with this connection String. But now we try to working with SQL Server Express R2. But above connection string not work with Express Edition. When we replace "." with "FBC-7PC\SQLEXPRESS" then our softwere work well with Express Edition. We want to use "." or only IP address not to use full name as ".\SQLEXPRESS". how can we connect with our epress sql server using "." or o ...