Promote method not increase generation number


I have a other question .. yet !!

I use the minor rev Handling  (

In the original method, the creation of a new minor revision does't change the part status to preliminary. 

So i addes the folowing code to the method PE_CreateNewMinorRevision:

Aras.Server.Security.Identity plmIdentity = Aras.Server.Security.Identity.GetByName("Aras PLM");

bool PermissionWasSet = Aras.Server.Security.Permissions.GrantIdentity(plmIdentity);

this.promote("Preliminary", "New minor revision");

 It works ..but the generation number isn't increase. 

How cant I increase this generation number ?