I set up 1 Roll-Up Summary and 2 Validation Rules based on information I found in the Help & Training section as follows:

To prevent create & edit to Opportunity Line Items on Closed Opportunities

Create a Validation Rule on Opportunity Product

1.  Description: Prevents users from editing opportunity products after an opportunity is closed. Create the following validation rule example on opportunity products.

2.  Formula: OR(ISPICKVAL(Opportunity.StageName, "Closed Won"), ISPICKVAL(Opportunity.StageName, "Closed Lost")) Error Message: Opportunity Line Items cannot be created or edited because the Opportunity is closed.

3.  Error Message:  Opportunity Line Items cannot be created or edited ecause teh Opportunity is closed.

4.  Error Location: Top of Page

AND

To prevent deletes to Opportunity Line Items on Closed Opportunities

Create a Validation Rule on Opportunity

Assumes that you have a custom Roll-Up Summary Field on Opportunity object called Number of Line Items, that Counts the number of Opportunity Product records associated to an Opportunity.

1.  Description: Prevents users from deleting opportunity products after an opportunity is closed. Create the following validation rule example on opportunities. It uses a custom roll-up summary field on opportunities that counts the number of   opportunity products on an opportunity

2.  Formula: AND(OR(ISPICKVAL(StageName, "Closed Won"),

ISPICKVAL(StageName, "Closed Lost")),

Number_of_Line_Items__c <

PRIORVALUE(Number_of_Line_Items__c) )

3.  Error Message: Opportunity Line Items cannot be deleted because the Opportunity is closed.

4.  Error Location: Top of Page

I have comfirmed that both of these Validation Rules are marked as "active", but these rules are NOT preventing anyone from changing or deleting Opportuntity Products. 

Any ideas why the Validation Rules are NOT working?

Are there permissions that must be change at the profile and/or role level to allow Validation Roles to work?