>>Michel,
>>Include "driver=SQL server;" with SQLConnectstring and change true to yes (didn't try with true before maybe it'd work too).
>>In VS2005 it'd work as is because it uses SQL native client and doesn't need driver specified.
>>For SQL2005 you can also use (if ODBC driver is installed):
>>Driver = {SQL Native client}
>>
>>
>>

>>lnHandle = SQLStringConnect('Driver=SQL server;'+;
>> 'Data Source = .\SQLEXPRESS;'+;
>> 'AttachDbFilename="D:\Visual Studio Projects\Test\Test.mdf";'+;
>> 'Integrated Security=SSPI;User Instance=yes')
>>

>
>I think the problem relies with the server name. I put the computer name but this doesn't work.

Just a SWAG, but in the Data Source isn't the ".\" syntax referring to the local machine? Is the SQL server you're trying to attach to on the local machine, or a remote one? If remote you might need something like

Data Source=\\MachineName\InstanceName