Tu problema es CSS y no PHP.
Cita: Don't mix with other components
Icon classes cannot be directly combined with other components. They should not be used along with other classes on the same element. Instead, add a nested <span> and apply the icon classes to the <span>.
Only for use on empty elements
Icon classes should only be used on elements that contain no text content and have no child elements.
http://getbootstrap.com/components/ No es que parezca que no se puede... simplemente, no se puede.
De cualquier forma, muevo tu tema al foro adecuado, tal vez allá puedan sugerirte alguna solución.