I've developed a module for Magento and it's supposed to support the versions 1.5+. I've developed it in 1.9 and it works with 1.6+. 1.5 crashes when trying to install with this error.
PHP Fatal error: Class 'Mage_Catalog_Model_Resource_Setup' not found
How can I support all the versions from a single code base if this class is not found?
Also 1.6 works fine but refuses to install from a package generated from 1.9. I tried generating the package in 1.6 and tried using this after cleaning up the Magento instance but no joy. Still the same issue:
CONNECT ERROR: Unsupported resource type