Nasty holes when creating path

Hi everybody. 

I've finished of modelling this one ( ill upload the model soon) in zbrush this is the fabric of the model and is an extract from the model itself 2 sided by the way so y've checked the double side tab on extract (this is for people that uses zbrush). Then i've imported it  on netfabb for repair any hole or welded vertex. And finally Ive imported it to zsuite to get it ready to print but this holes apeared i'm sure that i'm missing something and maybe some body can tell me what is it.

I've exported the model in obj. and stl (binari and ASCII).

Thanks in advanced for any help you can give.781


The walls are too thin. You should have at least 1mm. With the way the model is designed the slicer sees the outer shell as a separate wall... You have to fix that in the model by either getting rid of these inner hollow spaces or by increasing the thickness of the wall that surrounds the hollow space. 

Thanks andre i'll try some backface masking or remake it.