really simple validation: RSV Error: the field " xxx" doesn't exist!
really simple validationhttp://www.benjaminkeen.com/software/rsv/prototype/demo.php is very useful and easy to use.

However there is a very common problem for newbie:

RSV Error: the field " xxx" doesn't exist! Please check your form and settings.

the root cause is because of the "space" key.

root cause:
"required, field_name,Please input xxx"
should be written as:
"required,field_name,Please input xxx"

see the difference? the 2nd one doesn't have the space key.