Had this same problem, and my solution was that I didn’t have the plugin files inside a folder called “buddypress”. Rather, they were all loose in the “plugins” folder. Once I made a “buddypress” folder in “plugins” and dropped the files in, all I had to do was reload the admin page and try again. Smooth sailing from that point on.
FWIW, I had this problem, and the solution was that I did not put the BP plugin files into a “buddypress” directory, but rather had them lying loose in the “plugins” folder. Added a new folder under “plugins”, tossed the files in, reloaded the admin area and everything worked beautifully.
