Unable to set permission_id using AML as well as C# code

I am trying to change the permission for Part object but getting errors. Here is the AML I am using to change the permission. <AML> <Item type="Part" action="edit" where="item_number='CPR-002'"> <permission_id>708662930B5B484A98C088859500CC42</permission_id></Item> </AML> permission_id is valid.   Also tried following code to change the permission based on property ref (community.aras.com/.../). The permission_id doesnt change. string permissionName=""; permissionName = this.getProperty("description",""); CCO.Utilities.WriteDebug("DebugMsg", "Permission Name =" + permissionName); //Get the permission item Item permItem = this.newItem("Permission", "get"); permItem.setProperty("name", permissionName); permItem = permItem.apply(); if (permItem == null){ CCO.Utilities.WriteDebug("DebugMsg", "Permission with the name not found" ); // I have verified that there is permission with the description name } //Set the permission item for the context item //this.setProperty("permission_id",permItem.getProperty("id")); this.setPropertyItem( "permission_id",permItem ); // I have tried both the methods without any success return this;   Any help in this regard is highly appreciated.   Pravin