jQuery禁用按钮（不提交），直到字段验证+验证插件

I have 4 buttons on my form, a Submit, Cancel, Add and Remove button. All are working as expected but I would like to disable the Add button until the input field validates. I'm using the Validation plug-in and I think this can be done with a required validation with a callback but I'm not sure.I have 4 buttons on my form, a Submit, Cancel,