The user instance login flag is not supported on this version of SQL Server. The connection will be closed.

I have download an open source asp.net app. The database supported is SQL Express. When i try to run the app, error message [The user instance login flag is not supported on this version of SQL Server. The connection will be closed. ].

The reason is my installed database is full version of mssql 2005 and not express version. In order to make it run in my development machine, i have change the connectionstring in tag
<connectionstrings> from


<add name="TDConnectionString" connectionString="data source=.\SQLExpress;Integrated Security=SSPI;AttachDBFilename=DataDirectoryTD.mdf;User Instance=true"
providerName="System.Data.SqlClient" />

to


<add name="TDConnectionString"
connectionString="server=.\SQLSERVER2005;database=TD;uid=xxx;pwd=xxxxx"
providerName="System.Data.SqlClient" />

where ".\SQLSERVER2005" is my database server.

It's works now.