The first rule of magento development is one that I keep having to relearn every time I install magento. I am going to write it here, if only as a reminder to myself!

Disable the Magento cache. It’s great for speed on a live site but not necessary when developing. Many a minute has been wasted after installing a module that I know to be in a stable state and it not work due to inexplicable reasons.

To disable the cache. Go to your magento admin, then:

System -> Cache Management -> Select All -> Actions -> Disable -> Submit 

Confession complete.