I can’t get the slack.
Make sure there is no string tension, and practice!
Thanks
Along with making sure there is no string tension, make sure you’re popping the yo-yo up really far up to give you enough slack to work with. Pop it almost all the way to your throw hand- you need more than double the distance between your hand and the yo-yo worth of slack to catch it, so the higher up you get it the better. (In fact, if it doesn’t pop up at least some amount greater than 2/3 of the string length the trick will be impossible.) Then do the whipping motion while its up there. you may try to exaggerate the whipping move at first; your throw hand will end up almost completely up-side-down during the whip…
then for fun… after you land it, transfer the loop from you index finger to your middle finger. Then all of the string will be on your middle finger. Then you can loop the yoyo around your finger like a keychain. If you get your slip knot a little loose you can do this as long as the yoyo is spinning without wrapping your finger. then transfer the loop back to your index finger and bind.
I had trouble with this trick too at first. As everyone is fond of preaching, keep practicing. Once you hit it a few times you’ll get the feel of it and it gets easier. I hope that helps.
make a swooping motion with your hand as you try to fling it into the gap of the yoyo
thank you so much helped a lot
I only just started landing this trick consistently today and mofoya pretty much nailed on the head what I have been trying to figure out on my own for like a month now. Tut vids make everything look easy but it isn’t! what helped me a lot was trying to watch both the yoyo and the slack as a whole, which is hard to do unless you pop up the yoyo high enough. It makes sense to me now why doing it this way is correct. once its in the air whip the slack over with a kind of up and forward motion while everything is still “weightless” and you will find it much easier to land it! hope this helps! I’m still pretty newish my self!
Thanks everyone
In addition to the hop in the air, I think of it as a “throwing” motion. I throw as if the string isn’t tethered to my finger and the yoyo, aiming for a gentle lob forward. Not whipping down, but throwing forward. The loop HAS to go down because it is in fact tethered, so throwing forward will give a nice big open loop.
Bonus bind: do the whole trick over your NTH forefinger. Or more accurately, start the “throw” and at the same time, move your forefinger behind ALL of the strings. When the loop hits, the entire formation will be draped over the front side of the NTH forefinger. Release the loop from your throwhand, and the motion of “flipping over” the NTH forefinger will automatically pop the loop into the gap for a bind.
Works very consistently when you know the responsiveness of your yoyo… in some rare cases (huge gap, thin string, old pads) it won’t bind. Then you can either swing forward a bit first, or skip the trick altogether on that particular yoyo. 
Learned this one from John Higby himself, so I think of it as the Higby Bind. No idea if he created it or if it already has a name or not.
Also, one thing I noticed that really helps, along with what the other guys posted, is to try and keep your thumb pointed in an upward slant, in order to keep the slack from jumping off your thumb when throwing in a up and forward motion to land the trick. Hope this helps and good luck. Keep us updated.