What is wrong in my Salesforce Trigger Test Class which updates IsUnreadbyOwner field to False?

I have written a simple Salesforce Trigger. I want to update the IsUnreadbyOwner field to False once a lead becomes unqualified.

My Trigger is:

trigger UnqualifiedLead on Lead (after update) {
    for(Lead lead: Trigger.new)
    {
        if (lead.Status == ‘Unqualified’)
        {
            lead.IsUnreadByOwner = False;
        }
    }
}

My Test class is:

@isTest
private class UnqualifiedLeadTest {
    static testMethod void myUnitTest() {
        // Setup the lead record
        Lead lead = new Lead();
        lead.LastName = ‘last’;
        lead.FirstName = ‘First’;
        lead.Company = ‘Company’;
        lead.Status = ‘Unqualified’;
        lead.IsUnreadByOwner = True;
        insert lead;
    }
}