gradient question

i'm trying to make a transparent to black gradient saved as a .gif, but i keep running into some problems.

this is the gradient before i save it as a .gif to preserve the transparency:



i was just wondering if there was a way to make it smoother, because the black seems to be very "abrupt" and not too smooth.

also, when i do save it as a .gif this is how it turns out



and i've tried saving it for web and messing with the settings but everything turns out so pixelated and not very smooth at all ):  also because i want it to be transparent, i can't save it as any other file type.

i've also tried doing a black canvas, and then erasing some black on 0% hardness but it's very spotty.

i hope i'm making sense!

well, any help would be appreciated, and thanks in advance!



ETA: solved!  thanks heartagram_lala and pourboire!