Coopers australian draught lager

[craig133]

So i made some coopers australian draught lager everybody that has tried it say's it's got a bitter aftertaste any ideas i've recently found out when lager is in clear bottles keep away from light unfortunately i didn't know this would this be the cause or is it or is it change in temperature when fermenting although i use a brew belt which near enough case the temperature equal thanks for any input.