Problems with CD2 reporting invalid disc

CD1 is a 90ES. CD2 is a 70ES. Many times CD2 will not play and reports back invalid disk and then unloads. On an alternating playlist, basically the only thing that will play will be CD1. It attempts to load the CD2 and then skips to the next CD1 track. If however, CD2 starts playing, it seems to work ok. Does CDJ check to see if the proper disk is loaded? Could it be that the data reported by CD2 is not getting back to CDJ correctly due to the extra slink cable connecting CD2 to CD1.

There is approximately 50' of twisted pair wire connecting CD1 to the Slinke.

CD1 invariably plays correctly.