[Fizzlemizz]

Your code:

function(unit, cache, textframe)
    if UnitPowerType("player") == 0 then
        local z = math.max(0, UnitPower("player")) / math.max(1, UnitPowerMax("player")) * 100;
        return string.format("%.f", z) .. "%%";
    else 
        return UnitPower("player") 
    end

Proper code:

function(unit, cache, textframe)
    if UnitPowerType("player") == 0 then
        local z = math.max(0, UnitPower("player")) / math.max(1, UnitPowerMax("player")) * 100;
        return string.format("%.f", z) .. "%%";
    else 
        return UnitPower("player") 
    end
end

Proper indentation helps.