Here's why Beyonce's sis Solange fought with Jay-Z in hotel lift

Beyonce's sister Solange had a fight with her brother-in-law, Jay-Z, after he made plans to attend Rihanna's Met Gala after-party without his wife, according to reports.
A source told The New York Daily News that the fight between the two in the Standard Hotel elevator was set in motion 15 minutes earlier when a group of Solange's non-famous friends showed up uninvited for the Met Ball and caused a scene downstairs.
READ: Beyonce's sister Solange attacks brother-in-law Jay Z in lift
The insider said that the uninvited guests wouldn't leave and kept dropping Jay-Z's name.
This led the management to go to Beyonce's bodyguard Julius and told him that there was a problem.
READ: Beyonce's sister beating Jay Z clip spawns internet memes
The source said that the 44-year-old rapper got wind of it and snapped at Solange, saying not to use his name, which made Solange turn sullen and wanting to leave the party.
A second source said that on their way out, Jay Z said that he would be going, sans Beyonce, to Up and Down on W. 14th Street where Rihanna was holding her own Met Ball after party.
This apparently didn't sit well with Solange.
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WATCH: Solange attacks Jay Z