imadd command not working on my pc

I just discovered that when I try to run 'imadd' command on my PC, I get this error below, it was working perfectly ok before now,but when I did the same in a friend's PC, it worked. please what can I do to correct this.

>> a = imread ('c4.png'); b = imread ('c5.png'); c = imadd (a, b, 'uint16'); imshow(uint8(c/2), [])

??? Error using ==> imadd Too many input arguments.

Answer 1

[Walter Roberson]

Which release are you using? The ability to specify an output class has never been fully documented in the main imadd() documentation, but the facility has appeared in one of the examples as far back as Mathworks's documentation archive goes (R13)

[kiki]

I'm using 2007 version, the same version my friend is using.

[Walter Roberson]

which -all imadd

in case you somehow have an old version that is getting used.