If your composition is outputting graphics, audio, or other information that’s different from what you expected, then you should check the data flowing through your composition. Here are some things to check:
Where exactly does the data go wrong?
Check each port popover along the way to see if it has the data you expected.
Add some nodes to the middle of the composition to help you check the data (for example, a Render Image to Window node to check the data in an image port).
Is there a node whose output data is different than you expected, given the input data?
Read the node description carefully. The node might work differently than you expected.