Hiding the States list unless required

[PFE]

I have tried doing this from the script in the Advanced Used Guide and all seemed to work OK. I have split the UK into Areas and added that sucessfully so the state list appears.

What we have now found, due to some testing, is that if someone selects the United Kingdom but ignores the "statelist" it throws up an error requiring the "state" to be selected but the "statelist" box is hidden. Something changes between the initial display of the page and the one showing the error.

Any ideas what I have done wrong?

Thanks.