I just started messing with OpenComputers to automate Villager trading, and I can't figure out what my problem is. I have a Tier 2 robot with 3 Inventory Upgrades and a Trading Upgrade, trying to trade 26 coal for an emerald, but it tells me I don't have inventory space. I've tried moving the coal out of the selected slot and moved the selected slot from slot 1, but no luck. What am I doing wrong?