Be careful with Pixeltests when you are using acceleration.
I think what happens here is the following:

imagine Y=55*256 + 255
your sprite is displayed with a one-pixel gap between the sprite and the ground line because  Y/256=55.996  is truncated to 55 in Axe. The pixeltest returns false.
Now your acceleration is at 257 or more.
In the next loop  Y=55*256 + 255 + 257 = 57*256
your sprite is displayed at Y/256 = 57  this is already on the ground line. The pixeltest which tests the row under your sprite returns false because the ball has already crossed the line. Now there is no way to stop your ball from falling further off the screen.

This can not only happen with the values I pointed out above but always if the acceleration is more than 256. The ball can skip certain pixel lines then and the same can be at the vertical walls.

There are three different solutions I can imagine:
A: Draw multiple lines on the ground (I wouldn't do that because the ball may kind of sink into the bottom lines and stay there
B: Keep the acceleration under 256 (this shouldn't be a problem  )
C: Don't use pixeltest but check if the ball is lower then the last line (somthing like  Y/256>55  be careful then with the negative Y when the ball goes offscreen at the top  then you may use  Y/256>>55)

In my opinion version C is the best because I think it's the most clean and the fastest solution   

I have a question.
Can menu hooks be used to block or hide certain menu entries of the TI-OS menus.

5669:  You use hexadecimal numbers in your math class

In fact you can do that with the ScanF() function. You pass the lamda which returns the adress of the subroutine as the first parameter and make somthing like Pxl-On({->r1}...  to store the pointer given in HL to r1 and use it further.

By the way I forgot a command in the DelI() function. I will post a update tomorrow (with Get() function to get a pointer to a specified element and Length() to easy access the length of the list.

Edit: Here it is. Hope I didn't make any mistakes yesterday night 
       I'm going to make an example program soon

So here is a first readme with an explanation of all the commands.

I plan to make a Length command and a Reset command that clears the list (array).

That's exactly what I meant with "refuse God's love"

Thank you a lot 
I will try it. But for now it isn't a problem anymore because I found
a way to write the code without the 16bit load command.

Hell isn't really a popular term in mormon sects. The general term used is Outer Darkness, described as being filled with weeping and wailing and gnashing of teeth (from the other inhabitants of said place). This place is reserved for those who knowingly reject the atonement, e.g. participation is 100% voluntary.

I don't know much about the mormonism but i think this is also the catholic image of hell.
Nobody has to go to hell because god want's to save everyone, but humans are created as free individuals.
So everybody can refuse God's love and can live without him in eternity.
This place without God and love is called the hell.