Why is graphviz producing a corrupted image file?

I am using graphviz to create a png file, however when I run my the code, after it generates the image, I try to open the file only to receive a message that either the image file type (png) is unsupported, which I tested using other pngs so I know that can't be the case, or that the file is corrupted. The code I'm running is as follows:

dot -Tpng test.dot -o test.png

with test.dot being:

graph G {
  fontname="Helvetica,Arial,sans-serif"
  node [fontname="Helvetica,Arial,sans-serif"]
  edge [fontname="Helvetica,Arial,sans-serif"]
  layout=fdp
  "Infinity Blade" -- "Undertow";
  "Infinity Blade" -- "Shadow Complex";
  .
  .
  .
  "Calvin and Hobbes" -- "XKCD";
  "XKCD" -- "Enders Game";
  }

When running the code I did also receive two messages, however neither of them had resulted in a corrupted file the first time I received them:

Warning: Overlap value "prism" unsupported - ignored
dot: graph is too large for cairo-renderer bitmaps. Scaling by 0.404306 to fit