Pandora,
Old bufo can be tricky sometimes. I've had results where it literally goes exactly as the tek states, and others that are almost unsalvageable... and those are with the same stock of seeds.
The red brown that you mention has happened to me many times too. When that happens I let the seed/base mix dry out and pull with acetone again. At that point, the solvent takes on a real nice yellow hue. I then proceed with the fumaric acid step, however, I don't decant the acetone like Fractal said(going to try that next time though). Once I add the fumaric acid, it turn super cloudy with precipitates. I let that sit, and after an hour or two you can see bufo fumerate forming through the acetone. I usually extract at night, so I let the acetone sit overnight. In the morning, the once cloudy acetone is now nearly crystal clear. Decant that to reveal your bufo fumerate. Proceed with the tek, and good luck...