Ipod touch won't go into the incase case

I bought an incase case today, this one here: http://www.goincase.com/products/detail/slider-case-cl56302

It has 2 pieces, i tried putting it on and it wont go in! when i put both of them on together, the sleep/hold button(on ipod touch) wont go all the way up. and then the bottom cover for it, wont connect w/ the big case. There would be a space left in the middle/bottom. It cant seem to fit.

Is there any tips for putting it on? I tried many time but it will not connect, its fine when i put the ipod touch in but then it starts to get harder to put in when its near the hole for the sleep/wake bottom

is there anyone who use an incase for their ipod touch and had no trouble putting it in?

if so, can you tell me how can i put it in right so it can fit all the way. the case gave my ipod touch a few scratches