How to give offset animation to Emitter

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i made a dissolve material look like burning and I also made some sprites looks like ember and flames for it and i tried the shape location and float from curve to make the sprite to track the dissolving position.
However the Sprites just spawns at the key 0 of the curve and moves to key1 of the curve
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i expected the box location to move by the left in time but it just grows in size.
Might be great if i can get the information from the dissolving material and use as the position for the sprites to get emitted
Give any tips Plz

I meant the sprites just spawns every frame from the curves key0 to key1

Animate Shape Location in Unreal Engine 5.4 Niagara Tutorial https://youtu.be/pEWXxvYbwHc