I was told that 
>If net external moment of some forces is zero about a point, then the net external force passes through the point.  
  
I know it's not true in general, what was the special condition imposed which I forgot to include to make it true? Also, is there anything close to the statement we can say?
  
Some of my friends guess that if the additional condition that **the net external force on the body is zero** would be also imposed the statement might become true, while some say that the forces were meant to be co-planar. I do not understand why that would be true. It will be a great help if someone could provide some insight into what exactly is happening here.    
 
Please ask for clarifications if something is not clear.