Getting 'Subscripted assignment dimension mismatch' error when my image dimensions match?

I am trying to overlay one image on another and I keep getting a dimension mismatch error. Here is the relevant block of code:

img = imread('image');
pass = imread('passimage');
v6th = size(img,1)/6;
h6th = size(img,2)/6;
img(round(v6th-size(pass,1)/2):round(v6th+size(pass,1)/2),1:size(pass,2),1:3) = pass;

For reference:

size(pass) == 26, 64, 3

size(img) == 1051, 1425, 3

I have checked that round(v6th-size(pass,1)/2):round(v6th+size(pass,1)/2) evaluates to 162:188 totaling 26.

I am trying to eventually end up with something like this:

Answer 1

[Image Analyst]

162 to 188 is 27 numbers, NOT 26.

>> length(162:188)
ans =
    27

Recheck your math.