wrong error message.

hi – can you fixed error message
when I try register two times same email – a get just error

’empty_all’ => __(‘ERROR: All fields are required.’, ‘simplemodal-login’)

but I need get error

ERROR: This username is already registered, please choose another one.
ERROR: This email is already registered, please choose another one.

if I enter wrong email address – I get same error Instead Email not valid or something lije that.

Please fixed it or share some code how I can fix that

Big Thanks!

http://ww.wp.xz.cn/extend/plugins/simplemodal-login/