How long have you had the lavender and the violas?

Runner beans take longer than French or stick beans to produce actual beans, when did you plant them?

You can sort the lavender by cutting it back after flowering.You aren't doing anything wrong with your beans. More likely due to the weather or a shortage of pollinaters, though as MG says the first flowers often don't set beans.
Do you have plenty of bees on your lavender?
You could try gently spraying the flowers with a fine jet of water in the evening.