Madonna won't attend same party or event as Lady Gaga

Madonna does not have good terms with Lady Gaga. She will not attend the event if Lady Gaga will be attending it as well.

One source said, "It's unusual for Madonna to be so petty. She doesn't usually act like this, even about bitter enemies such as Sean Penn and J-Lo. But she didn't want to be forced into a photo-op with GaGa."

Source