Error even after adding reference to the project

#### Issue details
as per #1710 , i added reference to the project as u said but again when i built it , it gave the same error.
after adding reference i was adding system.speech but it wasn't there in the suggestion list, n it came in grey words.
how do i resolve this ?


Review the related issue #1710 and the attached screenshot first, then reproduce the build after adding the project reference and attempting to use System.Speech. Identify why the reference remains unavailable in the suggestion list and confirm that the project builds without the reported error.

Written by the indexing model from the issue text.