Disappearing Runner Beans

Hi
my mum is growing beans this year. Unfortunately the bean plants have flowered but the flowers are now dropping off and leaving no beans!!Doea anyone know what her problem might be?
Thanks

 

try a mixture of sugar and water, mix well in watering can and water with th mixture, it will attract the pollen loving creepy's in portugal, but the citrus from the oranges will attract all the pollen lover's you need, as long as they are not to chosey