My Seedling are Dying and Turning Yellow

I started germanateing 5 days ago 2 says in it they where vary long so I put them in my rockwool cubes 1x1 then 2 more days into it I notices that it was growing tall put not rooting into the cubes. So I put that cube in a 3x3 cube and into the system but day later they all droped dead and turned yellow. Can anyone help?

seedlings grow tall and lanky when they aren't getting enough light, sometimes to the point that they fall off. If you have more seeds, I suggest you start over, and give better light.