So in this code, I'm trying to insert `_` to an array but I don't really know what's wrong with this code. Because it seems to get stucked when the `_` is being inserted to the array. Is there better way to implement or fix the code?

```
.data
strUnderscore BYTE 20 DUP (?)             ;the array
.code
mov ECX,stringLength 
mov ESI, OFFSET strUnderscore 
L1: 
mov strUnderscore[ESI], '_'            ;the code runs but stucks here
inc ESI 
loop L1

mov EDX, OFFSET strUnderscore 
call WriteString

```