Furnace Issues

When I tried to insert fuel into the furnace, it wouldn't let me and when I tried to get the item I was smelting out of the furnace, it wouldn't let me. I expected for me to insert the fuel and item to be smelt and get the resulting item and be able to retrieve the items when finished.
What actually happened was I wasn't able to smelt the items because I couldn't put any fuel in and I wasn't able to retreive the items.

Steps:
1: Get fuel and thing to smelt.
2: Place items in furnace. Issues come up.