It would help you can provide detection names from other vendors. Also note that some malware are VM aware, so they wouldn't run the same code as when installed on physical.
Try running McAfee command line scanner to check if you are missing something in the configuration.
The most common reasons for missed detection by my reckoning, are -
1. Incorrect scanning configuration
2. Inadequate DAT and/or Engine
3. Invalid testing methodology
4. A root-kit has compromised the system
1 & 2 are easiest verified by examining the registry settings for the product. This is collected by the Support minimum escalation requirements tool (MER).
# 3 requres a step-by-step explanation of what you do to reproduce the problem.
This type of need is best solved by contacting McAfee Support.