Mordred (5/21/2013)
You'll need a default connection even if you are setting the actual connection with an expression that evaluates at runtime.
Where do I set the default connection? I'm going to start looking now and will post an answer when I find it but if someone posts before I do I'm going to keep checking here.
I think that the poster means the design-time value of the variable which the connection uses - as can be seen in the Variables window.
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.