# Power Up Man v1.0 **URL:** https://forum.makecode.com/t/power-up-man-v1-0/3883 **Category:** Arcade **Tags:** game **Created:** [October 14, 2020, 7:25pm UTC](https://forum.makecode.com/t/power-up-man-v1-0/3883 "2020-10-14T19:25:33Z") **Posts on this page:** 1 **Showing post:** 4
### Author: ![cosmoscowboy](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/cosmoscowboy/32/1718_2.png) [@cosmoscowboy](https://forum.makecode.com/u/cosmoscowboy) #### Post date: [October 15, 2020, 6:52pm UTC](https://forum.makecode.com/t/power-up-man-v1-0/3883/4 "2020-10-15T18:52:09Z")
> [@FlintAsher](#): > > Also for some reason sometimes when i shoot an enemy the game will come up with an error that says ‘failure to call on null’ I’m glad it works for everyone else cause i have no idea how to fix it. I think this has to do with this block. ![image](https://us1.discourse-cdn.com/flex020/uploads/makecode/original/2X/0/02509cafa979807ff5ee63aeb8833443b19df557.png) If I understand this extension correctly, this event fires when the enemy’s health reaches zero, so you can decide what to do with the enemy. However, you are simply deleting a reference to an enemy sprite that was created in the game update loop. ![image](https://us1.discourse-cdn.com/flex020/uploads/makecode/original/2X/2/2f0498e51d205833ca7ee7b812629401100fc4d5.png) So I am guessing when another piece of code is accessing an enemy sprite somewhere, that maybe that reference no longer exists. I think what you need to do is this: ![image](https://us1.discourse-cdn.com/flex020/uploads/makecode/original/2X/3/31944dfb63a1171da35c44112602fd876caded51.png) You set a reference to the sprite whose status bar has reached zero, and then delete it. Give that a try and let me know how that goes. If you are unsure, you could ask @jwunderl as he made and/or announced the extension: [Status Bars extension (beta)](https://forum.makecode.com/t/status-bars-extension-beta/1847) --- _[View the full topic](https://forum.makecode.com/t/power-up-man-v1-0/3883)._