Try setting the Vcode field with some random text like, "TESTING!" to see if that value is set correctly into the field. If so, you've got that part of the problem working correctly, then we just need to focus on pulling the right vcode value and placing it there.
My guess is that you have the above part working correctly, but that you are not getting the right value to set.
As you are dealing with a repeating list, this might be a straight-forward fix, or it might involve using the current() function. Please do a little research into how to use the current() function using both the Site Search and the Forums Search. Try out what you've learned and then get back to me on where things are at.