Solidus_Beckham_Jr

I'm playing in franchise and I got an amazing WR in a trade. But for some reason he will NOT show up in the slot specialist list. They would rather start my receiving hb at the position. This guy is such a perfect slot wr its killing me that I cant make it one.    What am I missing? I tried putting him at various depths on the chart to see if that was it but no luck! I mean....its my franchise, I should be able to put anyone as a slot if I wanted right?