Rules being ignored

Hi,

I have set up several rules depending on weight ( 0-100g(£1.50), 101-250g(£2.00), 251-500g(£2.75) etc) and my products weigh 100g each. If I add 1 item to my cart it says the shipping rate is £1.50 (correct). If I add 2 items to the cart it says – “There are no shipping methods available”. I also get this message if I add 1 item with a weight of over 100g to the cart.
If I change the weight to 20g I can add up to 5 items (100g) ok, but if I go over 100g I get the “no shipping methods available” message.
If I increase the weight range of the first rule I can add up to the upper limit before getting the “no shipping methods available” message.
It seems as though it thinks I only have one rule and it’s ignoring the other rules that I’ve set up.

Cheers
Simon