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You might wanna be more specific on the type of gun you have, it will help narrow down the possible problems.

But here are some of the basics.
-Is your marker recieving a consistant amount of air?
-Is every part in the marker assembled in correct order?
-Has the marker been properly lubed?

If the bolt was upside down some guns won't even c**k and even if it does it should still fire, just wouldn't get any distance with it.. prolly wouldn't even break against plywood at point blank. one more thing you might wanna check is if your trigger is responsive, you might just need to replace the battery (if it's an electric trigger) or perhaps a mechanical failer within the grip, but as they've already said.. we can't give any kind of advice or other helpfull clues untill we get a better idea of what we're working with.