I don't have an AIX system to test on - will have to talk to my boss about that 
But, I think this is similar to something I see with Windows and Linux systems. Hyperic provides a rolled up CPU set of metics and a subset for each CPU instance, for example. The subset instances are pretty unique (i.e. CPU1 on system A doesn't have the same 'name' as CPU1 on system B) - so using the "This Resource" reference in the formula doesn't help.
Can you validate if this is the case in your environment? I suppose the same holds true for the mounts. I'll dig around to see if I can find a solution for this.