water leak into inside top cupboard

Hi,
wondering if anyone has had any similar problems and how they sorted it?

Auto-sleeper Nuevo ES 2007.

We have noticed that there appears to be water is ingressing into the top righthand corner of the upper cupboard nearest the over cab bed on the habitation door side of the motorhome. We have not noticed on the ceiling of the cupboard and just appears to be damp and not running and definitely appears to be worse after heavy prolonged rain (quick shower doesn't produce any damp in cupboard).
Above this area on the outside is the wind out canopy awning which is built in and not added afterwards and we wondered if this could be an area of issue?
There is a boxed in area in the over cab bed area inside which i assume has the winding mechanism for the awning? and this is next to the cupboard but there is no signs of damp around this.

Hoping someone may have experienced similar issue and could give us an idea of where to start and possible fix ideas. 
Thanks in advance for any help and ideas