Can you please invite all your friends at once?
ill show you how to do that. a simple way..


Go to the group page
and on the right side you shall see a button that says "invite friends"
Click on there then you will find a check box that says "all - none - invert"
or something similar.. just check the "all" button and you can then press invite..

Done.. that simple..
Please doo that

Thanks