well, if could read your code i would be pretty sure to be able helb you.
but let me try to help without reading it^^

if im right, you try to let the missile know what it has hit.
try, to detonate the missile an collision and do nothing else.
and let the poverup check if its been hit by player or missile.
than you could let it dissaper or powerup the player...

if this dindnt help, post your code so sombody con read and help^^