I always buy well rooted runners and make sure you buy them from a reputable grower who will guarantee they are disease free. I had some really good ones from Marshall seeds last year. Make sure you don't plant them too deeply, the crown should be only just level with the soil, and don't let them fruit the first year. They are hungry plants too. Did they flower well? If so it may have been they didn't get pollinated - plant some bee attracting plants nearby, or perhaps the birds/slugs/mice etc. ate them. Once they are set they need to be well netted. A potash feed helps to encourage them to flower/fruit - easily available. Not much we can do about the weather though. If it gets too cold early on you could try covering them with fleece but I am in the south west so never bother to do this, could be different if you are in the north.
