Sprite slicing problem

I have a problem.

I imported a sprite sheet into Unity with the following dimensions:

 1024 tall

 17664 wide

individual sprites are as follows:

 1024 tall

 768 wide

when I click the splice button, the menu pops out as it should with the correct options, but when I click splice (when I click splice if I have selected automatic, by cell, or by count) nothing happens.

The only notable things are a few errors in the console that are as follows:

 requested size is too large

 requested size is too large (not a typo, there are two of this error)

 texture has out-of-range width/height

 failed to create textures because of invalid parameters

help?

(upon further inspection, it appears something is too large, what can I do? Can i do something without creating a new spritesheet?)