I am almost finished, I just finished at Leathercombe Bay/Store-Chemist: did the powder packet on the test tube. Next I am suppose to "Watch Kenneth Marshall call and tries to wake up Linda." I can't find this, please help

This part is a cutscene. It will run automatically if all the required actions are already done in that chapter.

Double check the walkthrough to see if you missed anything. Also check your journal for any red actions and recheck inventory and any documents picked up.

thank you