PHP PsiReferenceProvider

Hi,

In Symfony plugin, the PsiReferenceProvider code that is registered with

psiReferenceRegistrar.registerReferenceProvider(
    PlatformPatterns.psiElement(StringLiteralExpression.class),

works, the reference provider gets called when being debugged when PHP string literal is clicked.

But my reference provider that registers the same way is not called, no matter how I try to trigger it on the string literal.
My registerReferenceProvider is still called though.

Why is this so?

Regards,
Alan