Not able to set 'readonly' on text input box

Is there any obvious reason why this input box is editable?

<input id="username" name="username" class="textfield70pc" readonly="readonly" type="text" value="My username" />

It 开发者_如何学Goseems kind of pointless having to use javascript / jquery to disable this text box.

If you're looking for it to be grayed out, add the DISABLED attribute:

<input id="username" name="username" ... disabled="disabled" />