Challenging behaviours can result from a range of different reasons.  Some of these include difficulties with understanding language, frustrations with communication, difficulties with social language, difficulties with adjusting to new environments, underlying medical reasons, challenges with processing sensory information (e.g. noise, touch, visual information) as well as many other reasons.  Challenging behaviours can occur in some environments and not others, and in some situations and not others.  It can often be difficult to work out the function behind the behaviour.