How To Connect To SQL Server Express 2005 Database At The Same Time From Both SSMSE And VB2005 Application ?

Here is the situation:

I have SQL server express 2005 installed on my pc as instance SQLEXPRESS.

I have created a Visual Basic applicaion with the following as connection to the SQL server express 2005 running on the same PC:
****************************************************************************************************
Dim lconnectionString As String Dim builder As New SqlConnectionStringBuilder Dim cmd As New SqlCommand Dim reader As SqlDataReader Dim parameter As SqlParameter builder("Data Source") = ".SQLEXPRESS" builder("Initial Catalog") = "" builder("AttachDbFilename") = "C:My DocumentsVisual Studio 2005Projectsabcabcabc.mdf" builder("Integrated Security") = True builder("User Instance") = True lconnectionString = builder.ConnectionString Dim sqlConnection1 As New SqlConnection(lconnectionString) cmd.CommandText = "SP_add_collection" cmd.CommandType = CommandType.StoredProcedure cmd.Connection = sqlConnection1 sqlConnection1.Open()
*******************************************************************************************************************

It seems that i can not connect to the abc.mdf in SSMSE while the VB program is running. (ERROR:
Database 'C:My DocumentsVisual Studio 2005Projectsabcabcabc.mdf' cannot be opened due to inaccessible files or insufficient memory or disk space. See the SQL Server errorlog for details. (.Net SqlClient Data Provider) )

If i connect to the abc.mdf first in SSMSE, then run the VB program afterwards, it gives me the error on this line -- sqlConnection1.Open()

I want to be able to access the abc.mdf database with both SSMSE and VB at the same time. Could anyone help me on this ?

Thanks very much !

apple