Multiple expansion works in rules, but not in actions

[Alexander Kriegisch]

Can anybody explain why this does not work?

FOO=bla
BAR=blu

$($(FOO)_xxx): baz
        @echo "$($(FOO)_xxx)"

Multiple expansion works for the target definition and possible
prerequisites, but not for the echo or any other shell commands inside
actions. Is this a bug or a feature? Can I somehow use multiple
expansion in an action?

Thank you and best regards
-- 
Alexander Kriegisch