What transaction set are you working with? 834, 837, 835?
You mentioned that you get this on the first occurance, but not the rest of the file. First occourance of what? First 2310A or 2420B?
Not knowing how your Iterates are set up, I would try to iterate into the 2420A loop from within the 2310B loop. This way you will get every 2420A for each 2310B segment.
