My guess, is that you forgot to take the linear nature of the $sp$ carbon-carbon bonds into consideration.
So the bond lines cutting through four carbon atoms will be linear, and not zig-zagged as in the rest of the molecule (the latter implies tetrahedral geometry accorded by the $sp^3$ carbon-carbon bonds)
What you probably drew:
As opposed to what the skeletal representation for your molecule is supposed to look like:
Crude diagram courtesy: MS Paint application
Okay, it might be better if you draw the whole thing with the (lone) triple bond parallel to the bottom of your page (i.e- aligned with the horizontal)
The first diagram may feel more "graceful" (the term I used when I defended my incorrect depiction of the triple bond to my teacher when he asked me a similar question a while back), but it is incorrect.
The red circles represent the carbon atoms in your molecule. They (red-carbon-circles) aren't supposed to be drawn in, but I added it for clarity O:)
P.S-
If it makes you feel any better, I had to draw and re-draw the (correct) skeletal representation of your molecule a few times before I got it right.
Kudos to your professor for the good question! ;)