Common issues and fixes
Problem
It's trying to loot an item but keeps failing.
Fix
Chances are it's a no drop item and you have no drop confirmation set in your EQ Options window. In-game, go to Options > General tab > No Drop Item > set to 'Never'.
Problem
It's missing items
Fix
First and foremost, are you sure? Try unhiding corpses and see if the item(s) are still on the corpse. The macro often loots items faster than the gui can update.
Do you have followme, stick, anchoron or something similar set? It's probably being pulled away from the corpse before it can attempt to loot anything.
Problem
How can I set the macro to always run?
Fix
You can't. I've always intended for it to be a macro you trigger on your own.