Chocolate Cherry Tomatoes

This year I thought I'd try a different variety of tomato and bought a Chocolate Cherry from our local Nursery. Selected a healthy looking plant and fetched it home, planted it along with my other toms in a sunny sheltered spot in fresh growing media in a deep planter box.
Now here is my problem :- it has grown well in terms of height etc and has produced several clusters of flowers but none have produced fruit !
It hasn't shown any obvious signs of blight and the other varieties of toms I've planted around it are all bearing fruit some of which is ripening.
Has anyone got any experiance of this variety who can advise me what's going wrong ?

Thanks in advance.

Not tried that one Mumofstig ! I'll give it  a try this afternoon 

Sorry to bring this up again but yet again the flowers have failed to set any fruit ! But another shoot has formed 6 or so flowers and the plant has grown a bit higher.
I'm really at a loss with this variity-all my other toms are yealding plenty of fruit of which I've started picking !
Has anyone got any worth while advice about these chocolate cherry tomatoes ? or shall I pull it out and give up on it!

Sorry to put a downer on things but i have 2 chocolate cherry tomato plants growing. Both in containers outside.

For about a month now they have had tomatos on them.. slowly starting to get bigger now but still quite small.. they seem to take ages to ripen!

Hope yours sort themselves out soon!

Judging by other threads, all tomatoes seem to be taking longer to ripen this year, mine are still green, maybe they are on their way?