What's 'it?'
I'm assuming you have a Researchable Defense Upgrade, and when you research it, the defense of your unit increases by 4. Am I right?
If that's the case, you'll want to edit your upgrade stats.
Also, I know it's unrelated, but try properly capitalizing your units' names. It's a real turn off when people play a map and the grammar is atrocious. It is for me anyway, it just makes the whole thing seem very sloppy and unprofessional. It's as frustrating as having incorrect or missing tooltips.