i want find a1.bmp, a2.bmp.... use Gdip

[WTF]

find(hwnd, byref vx, byref vy) {
pToken:=Gdip_Startup()
pBitmapHayStack:=Gdip_BitmapFromhwnd(hwnd)

i:=1
while(i<57){
pBitmapNeedle:=Gdip_CreateBitmapFromFile(a%i%.bmp)
if Gdip_ImageSearch(pBitmapHayStack,pBitmapNeedle,list,0,0,0,0,70,0x000000,1,1) {
StringSplit, LISTArray, LIST, `,
vx:=LISTArray1
vy:=LISTArray2
Gdip_DisposeImage(pBitmapHayStack), Gdip_DisposeImage(pBitmapNeedle)
Gdip_Shutdown(pToken)
EL:=0
return true
}
i++
}
Gdip_DisposeImage(pBitmapHayStack), Gdip_DisposeImage(pBitmapNeedle)
Gdip_Shutdown(pToken)
EL:=1
return false
}

but "pBitmapNeedle:=Gdip_CreateBitmapFromFile(a%i%.bmp)" is not work...

i can't find image

What am I supposed to do?