hi first post.i have used a junction box into existing light switch wire in my loft and taken new wire fron juction box two a new two way switch.i wired in the feed from the juction box L1 RED L2 BLACK AND EARTH TO OTHER ONE.when it comes to wire in the new light wire i just put them in the same way.the light comes on when switched mains back on but when i switch the light of at the new switch it trips the fuse in main box.i tried red/blue/black/red and the EARTHS together but this just tripped as well anyone any idea what im doing wrong.