vm's cpu and RAM settings missing

Greeting,

I had a vm already in one of the vapp.

for some reasons, the vm's cpu and RAM settings missing.

I highlight that vm's properties the goto tab "Guest os customization", check "Ebable guest customization"

then back to "Hardware" tab, change the cpu and ram setup back.

but I got error "cannot update"

can somebody give me a hint where is the start point?

thanks

newbie