Errors in XML can prevent the rest of the file from loading. If there's an XML error above what you posted, then that could be the culprit. Is there anything about it in World of Warcraft/Logs/FrameXML.log?
Unless you're seeing "Loading InstaBolt", in which case there's a problem in InstaBolt_OnLoad(). If you're not seeing Lua error messages, try putting debugging statements such as the following between all major code blocks to narrow down where the error is occuring:
Code:
DEFAULT_CHAT_FRAME:AddMessage("FUNCTION START")
--some code here
DEFAULT_CHAT_FRAME:AddMessage("POINT 1 REACHED")
--code
DEFAULT_CHAT_FRAME:AddMessage("POINT 2 REACHED")
--code
DEFAULT_CHAT_FRAME:AddMessage("FUNCTION END")