Since I see so many different things causing the 'Error: Please select another Shipping Method'. I thought I would just document the problem I had....
My shipping scheme is 'buy <5 and pay xx shipping' and 'buy >5 and shipping is free'.
In the shipping rate description I had added "Less than 5 item (+$50)". Well the code interpretes teh '+' as an operator rather than text. Replaced '+' with 'Add' and everything works.
G
I had the same problem, but I want to explain the solution a bit better.
When you define your "shipping rate" (in the menu : shipping => shipping rates)
you should be careful when you fill in the "Shipping Rate description"
I had problems myself when I filled in + or < or >
Success !
just to add ....
i had 2 to 5 kg's ..... the description doesn't like apostrophes either .... therefore it had to be amended to : 2 to 5 kgs