Dont really know if the pmimport.cab is incorrect, but you can always check the IsInstalled and IsApplicable rules to see if it is.
This should get you started.
Troubleshooting Patch Management Inventory - Applicable rules
https://kb.altiris.com/article.asp?article=42107&p=1
Patch Management Single Rule Evaluator
https://kb.altiris.com/article.asp?article=42072&p=1