Hmm...I don't see why they're not working for you - they have been the standard Photoshop shortcuts for resizing brushes since...well, I started off using Photoshop 6 and they were there then!
Maybe one or both of these links might help. This offers free downloadable PDF documents detailing all the Photoshop keyboard shortcuts for Windows and Mac, from
PS 5 up to CS2:
GFX^TM - Photoshop and ImageReady Tutorials, Actions, HotKeys, Free Lightwave 3D Models, Images and Icons
You can also create your own list of keyboard shortcuts as a HTML file from within Photoshop as follows: select
Edit >
Keyboard Shortcuts and then click
Summarize.
This link gives you a guide to editing and defining your own keyboard shortcuts:
Photoshop Keyboard Shortcuts | PhotoshopSupport.com