Cant plow as a hired hand..............?

i am currently a level 12 with 13 neighbors. i am trying to earn money and exp by getting jobs, however when i go to plow on someone elses farm it wont let me do it. whenever i try to plow it just turns the patch im trying to plow into a patch of gr... i have tried this many times to see if it just happened once or twice due to faulty connection or something but it wont ever work. someone hellp please