| Hi SanSingh. 
I downloaded your 3DM file and for what I briefly checked I think that the main problem are the Red and Blue curves. 
1) The red curve is a single curve made by two segments not well joined. 
2) And, furthermore, even the blue curve is one single closed curve.
 
As you can see in the video I have simply deleted the red curve and I trimmed the blue curve. 
Then I selected ALL and performed the Network command.
 
Hope this can help :)
 
Here's a video capture of Moi's screen : http://take.ms/B69p6 
Here's the modified Moi file : http://take.ms/qWMGB 
Here are some screenshots :
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