Macro help please - resizing thousands of images

Hi there, wonder if anyone can help me. I'm a bit of a macro amateur....

I have thousands of images that I wish to resize to 210mm wide.

I'm trying this but it's not working:

-Run Temporary Macro

-CTRL A

-CTRL G

-Then I type 210 into the 'width' box

- P (just to centralise it on the page)

-CTRL S

- Close page

- Stop recording

Then I load the images and press CTRL + SHIFT + P to run the temporary macro, it runs, closes the image down but when I go back and check it, it hasn't re-sized it!

Can anyone let me know please what I am doing wrong?

Thanks,

Mark