from T5.0.11 to T5.0.6

[Natia Gdzelishvili]

I change my application from tapestry 5.0.11 version to 5.0.6 and I'm
getting :
java.lang.RuntimeException Page Start did not generate any markup when
rendered. This could be because its template file could not be located, or
because a render phase method in the page prevented rendering.
what is wrong?