General
First, confirm that the areas shows anywhere. Regardless, this error is occurring due to an issue in one of two areas:
- Incorrect/missing/superseded files
- Incorrect/missing configuration
1. Incorrect/missing/superseded files
Diff a known-good copy of your version of Magento against yours. Correct any differences, restore files, and reset theme settings such that the "default" behavior should be in effect
2. Incorrect/missing configuration
You've confirmed that the configuration settings to display this button are set, but Mage_Adminhtml_Block_Catalog_Helper_Form_Wysiwyg::getIsWysiwygEnabled()
checks if the Mage_Cms
module is active to display even the disabled version of the button. Check that.
WYSIWYG Editor
button under description textarea?