Transition/animate individual sprite in a spritesheet-- Please Help!

I am hoping some one can help me figure this out. I create a spritesheet and add the individual frames in a table.  I am trying to transition or animate the individual frames, how can I do this?  Here’s what I tried in my for loop.

    transition.to(letter[#letter], {delay=500, time=500, alpha=0}) – this set all the sprites alpha to zero

        

     transition.to(letter[#letter+1] , {y=200, time=500, transition=ease}) – this does nothing.

    

Thanks!

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–                    SPRITE SETUP                –


local letterSheet = sprite.newSpriteSheet(“tiles.png”, 70, 65)

local letterSet = sprite.newSpriteSet(letterSheet, 1, 26)

sprite.add(letterSet, “letters”, 1, 26, 1000, 1)

local letter = {}

local mask = {}

local letterGroup = display.newGroup()

local maskGroup = display.newGroup()

–masks

for x = 1, 4 do

    for y = 1, 4 do

        mask[#mask+1] = display.newImage(“mask.png”)

        mask[#mask].x = x*70-15

        mask[#mask].y = y*65+70

        mask[#mask].isVisible = false

        maskGroup:insert(mask[#mask])

    end

end

–letters

for x = 1, 4 do

    for y= 1, 4 do

    

        letter[#letter+1] = sprite.newSprite(letterSet)

        letter[#letter].x = x*70-15

        letter[#letter].y = y*65+70

        

      transition.to(letter[#letter], {delay=500, time=500, alpha=0}) – doesn’t work

        

     transition.to(letter[#letter+1] , {y=200, time=500, transition=ease})  – doesn’t work

    

                

        letter[#letter].currentFrame = math.random(1,26)

        letter[#letter].val = letterList[letter[#letter].currentFrame]

        

       

        letter[#letter].mask = mask[#letter]

        

        localGroup:insert( letter[#letter] )    

        

        

    

    

        end

        

    

end

localGroup:insert( letterGroup )

localGroup:insert( maskGroup )

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