standart slicing not working on my vector

Hello i Have the following code:

val=fscanf(ser);
var_hex=dec2hex(uint8(val))
y = reshape(var_hex.', 1, [])

which gives me size 1 12

when i try to do y(1:8) it gives me an Index exceeds matrix dimensions.

Why its not slicing such array?

[Stephen23]

val = [1,23,0,99,255,5];
var_hex=dec2hex(uint8(val));
y = reshape(var_hex.', 1, [])

y = '01170063FF05'

size(y)

ans = 1×2

1 12

y(1:8)

ans = '01170063'

[fima v]

is there some other method? y(1,8) says it exceeds.

Its a callback function i cant see the variable as variable.