getElementById & onclick Button function won't work

getElementById & onclick Button function won't work

References

Reference NO 1

http://stackoverflow.com/questions/15186244/getelementbyid-onclick-button-function-wont-work

Reference NO 2

http://stackoverflow.com/questions/10835687/javascript-function-wont-fire-on-button-click

Reference NO 3

http://w3schools.invisionzone.com/index.php?showtopic=45473

Reference NO 4

http://social.msdn.microsoft.com/Forums/ie/en-US/e32a1d38-b8a0-4040-87bc-1831e5552a66/action?threadDisplayName=onclick-function-doesnt-work

Reference NO 5

http://javascript.info/tutorial/introduction-browser-events

Reference NO 6

http://www.javascriptjedi.com/getElementById/

Reference NO 7

http://cs.lmu.edu/~ray/notes/javascript/

Reference NO 8

http://www.w3.org/wiki/Handling_events_with_JavaScript