"We had good chances and if we had taken them it might have been a different outcome but we have been saying that for weeks now," Williamson said after the game.
"We have just got to keep working hard, and eventually I am sure we will get the breaks we deserve.
"Credit to Derby - they defended well and played well in the second half. The first goal was important and it came off one of our defenders.
"We had a lot of pressure but could not get on the end of it when it dropped in the box. We have got to hit the target."