SSIS DTS Package won't log in

I have the following in my .dtsConfig file:
***
*** *** Data Source=myPC\sqlInstance;Initial Catalog=QISUAT;Provider=SQLNCLI.1;User ID=user;Password=xxxyyyzzz123;
***

But I keep getting this:
Error: 2008-04-09 11:50:42.91
** Code: 0xC0202009
** Source: Package Connection manager "QIS"
** Description: SSIS Error Code DTS_E_OLEDBERROR.* An OLE DB error has occurred.
*Error code: 0x80040E4D.
An OLE DB record is available.* Source: "Microsoft SQL Native Client"* Hresult: 0x80040E4D* Description: "Login failed for user 'qisuser'.".
End Error


If I drop the connection string into a .UDL file, and test, it works fine. What am I missing?

SQL 2005 dev is running on my system (myPC) and I'm running dtExec from my local command prompt.
H:\>"C:\Program Files\Microsoft SQL Server\90\DTS\Binn\DTExec.exe" /File C:\CSCQIS\ImportProcess\SSISPackages\RegistryInitialLoadPackage.dtsx /ConfigFile C:\CSCQIS\ImportProcess\SSISConfigFiles\RegistryInitialLoad.dtsConfig