I'm at the "pot making", about a third of the way along. At the kiln, I made the fire and put it into the kiln. I used the sealskin on the bellows to repair it. Now I'm supposed to use the bellows and place the unfired pottery into the kiln to get pots. I puff and I puff on the bellows, but each time I get the same response when I put the pottery in. "The fire is not hot enough." I can't seem to get enough pulls to satisfy and I tried for sevrral minutes. Any suggestions?