Yahoo Mail problem on iphone

[hikemail]

My yahoo mail worked perfectly on the mail application on the iphone for the first 6 weeks or so. Now it tells me that I have a wrong ID or password. I've changed nothing, and the account works fine on a computer and on safari on iphone. Everywhere except the iphone mail app. I've tried reentering the details without success As I like(d!) the mail app I would like to get it working again. Help!