Player wont cast spell.

[Rock Lee]

Could somebody please tell me what is wrong with my macro?

/run local h=UnitHealth("player")*100/UnitHealthMax("player") if h<=75 then /cast [target=player] Lesser Heal end

[Twinzlol]

should there be percentiles? like 100% and 75% instead of whole numbers?

[Rock Lee]

Yes. 75%. Forgot to mention that.

[Ssateneth]

/run local h=UnitHealth("player")*100/UnitHealthMax("player") if h<=75 then /cast [target=player] Lesser Heal end

Change to...

/run if UnitHealth("player")/UnitHealthMax("player")<=0.75 then CastSpellByName("Lesser Heal","player") end

I'm assuming you want your macro to cast Lesser Heal on yourself if you are at 75% hp or less. If you want to do this for another person, you'll have to put "target" where it says "player" and have them manually targeted. If you want to automate healing for a party/raid, though, then you'll need to do something more complicated, possibly something with a while and do.

Note: This only works if you have protection disabled for protection LUA functions, either from NoAddiction or LuaPulse, but LuaPulse will be unable to run the macro ingame as far as I know.