my last activity on the project was finishing lets say on November 1. When I put a finish no later than constraint to the last activity as something before november 1, such as October 31, it reduces the toatl float by 1 day and makes the total float of critical path as -1, which i understand

but when i put a finish no later than constraint to that activity as november 2, nothing changes. should this not increase the total float of critical path?