E-Sign Text Tag Question

Hi There,

I am working on a project which requires Adobe E-Sign Service. My solution is using the Text Tag to specify the signature spot in my application. Then, send the generated PDF file to the E-Sign service.

In my application, I am preparing the Text Tag with Annotation. I am using this syntax "{{_es_:signer1:signature}}" for the Text Tag. However, Adobe E-Sign service doesn't recognise it. Does that mean Text Tag within Annotation is not supported?

Thanks so much
Jing