Even though he and estranged wife Brooke Mueller have reached a settlement over custody of their twin sons, embattled actor Charlie Sheen won't see his boys for their second birthday Monday.

As Breaking Celebrity News first reported, sheen, a dad-of-five, was locked out of Bob and Max's birthday at Rick and Kathy Hilton's mansion in Bel Air, California, on Sunday.

The famous father wasn't on the invite list, and now we've learned he won't even get a chance to wish the gorgeous boys happy birthday, in person, on Monday either.

Sheen hasn't seen the twins since cops made him surrender them to Mueller -- the emotional moments all caught on our cameras.

"Brooke will have custody of the twins on Monda,y and they will not be seeing Charlie," a source with knowledge of the custody arrangements told Breaking Celebrity News.

As we previously reported, Sheen and Mueller struck a custody agreement late on Thursday -- the terms of which remain confidential.