Running DTS package - Invalid Authorization specification

[Elmo Watson]

I'm trying to run a DTS package through VB.Net code (after having imported
MS DTS com library):
Dim mDTS As New DTS.Package
Dim mDTS_Server As String = My.Settings.DTS_Server
Dim mDTS_ID As String = My.Settings.DTS_ID
Dim mDTS_PWd As String = My.Settings.DTS_Pwd
Dim mDTS_Proc As String = My.Settings.DTS_Pkg

mDTS.LoadFromSQLServer(mDTS_Server, mDTS_ID, mDTS_PWd,
DTSSQLServerStorageFlags.DTSSQLStgFlag_Default, "", "", "", mDTS_Proc,
Nothing)
mDTS.Execute()

the ID and password above are both valid on the server, and the Server and
package show up find, stepping through the code.
However, I still get the Invalid Authorization specification error.

Any ideas?