Super Metric works only few clusters not all

I have created a super metric to calculate the memory of cluster. I am getting results for only few clusters remaining clusters the result is " - ".

sum(${adaptertype=VMWARE, objecttype=VirtualMachine, attribute=mem|consumed_average, depth=4})/(1024*1000*1000) - This is the super metric which i am using, please help.

And one more SM i have created but that one output is just "0". For the same above mentioned purpose tried with this metric.

sum(${adaptertype=VMWARE, objecttype=VirtualMachine, attribute=mem|guest_usage, depth=1})/(1024*1000*1000)

thank you.

Krish.