Are you keeping them well watered and spray the flowers in the evening when the suns not on them and then give them a gentle shake to free pollen just like you do with tom`s. HTH`s
There is an increasing problem with bee colonies dying out, so could be a pollination problem. Shylock`s correct, you`re going to have to give them a helping hand.
plant sweet peas on every other sick there is no need leave the bean out on that stick
try planting as many scented flowers around you garden
put bunches of mint on your bean row it helps to keep
black fly away change every week