matrix recursive element

Hi, I want to run this code

Code:

local filas = 300
local columnas = 1
matrix A = J(`filas',`columnas',0)
matrix A[1,1] = 1
forvalues i = 2/`filas' {
matrix A[`i',1] = matrix A[`i'-1,1] + rnormal()
}
matrix list A

but, when

Code:

matrix A[`i',1] = matrix A[`i'-1,1] + rnormal()

is excuted stata shows "matrix not found".