It would seem like you lack sufficient materials to exchange.

I've had the same problem. Also, check again. It's quite obvious that he has plenty of material for a Cave Key or a Summoning Scroll.

Have you made a lot of exchanges? I guess they are capped. I can't exchange anymore for keys while I can still exchange for other items. This post was last edited by Giizis at 2017-1-24 23:28

I've only ever exchanged for the keys

yeah the key is capped at 10 or sth, go get summon scroll instead, had the same issue

thats the issue it'll only let me get Ramen nothing else even though I can clearly get summon scroll

This was answered in Customer Service section.

Apparently, we're supposed to be able to exchange for only 1 of each, but the coding somehow allowed us to exchange 4 of each (according to some players, and personally, I changed for 4 keys and I can't anymore as well). So if you're already exchange for 4 keys, you'll just have to change for something else.

well that'd be awesome if I could but it won't allow me to go for something else only the Ramen and I've never exchanged for either of the scrolls or the magatama and I see that I only have enough for the summon scroll but it won't let me exchange for it.

There is a limit set on the exchanges. If you have a scroll wheel on your mouse you can scroll down on "available to" and it will show the limits and how many you have left. The limits being:
5x Key
2x Summon Scroll
2x Attack Mag
2x Seal Scroll

I figured it out. apperently after I exchanged for the key the number of pencils never changed. it fixed it self once I got back to that amount