Sounds like the brassicas either did not germinate/grow, or were ate as soon as they emerged. Alot of the off brand mixes have Rye Grass as a good portion of the seed. I' m thinking that' s about all that you have, maybe a little timothy too. While not a preferred food deer will nibble at it, especially when its young.

Woodland food plots if smaller than 1/4 acre generally do not fare very well. The exception might be a september planted winter wheat or cereal rye, planted very heavy (100-120lb/acre) with 300 lb/acre 20-20-20 fertilizer.