Did you read the diary completely and know what each lock can be opened with?
- The sixth seal is opened by the invisible key visible to all.
Did you examine the painting completely by clicking on the Van Buren, wolf, etc?
Did you click on the key that is on the table after reading the diary?

dear MaG.
THANK YOU,THANK YOU,i followed your instruction's,then i got
the key,seal 6 is now open,i have another problem,wilbur must summon the arch-mage ghost,i did what the WT says,but the last step to draw his symbol,he does not want to,he says,he does not know the symbol,he refuses,i took wilbur
to the mirror to look at,nothing moves i am stuck,PLEASE HELP,i thank in advance
samuel

The walkthrough has the step by step.
Did you get the mail from the mailbox and give it to the count?