Butt plug too long?

I've recently bought a prostatic telescopic butt plug on AliExpress.

I'm having trouble getting it completely in, like it will go in like 90% of the way, but I can't get it past the last "ball". I've used wider but shorter plugs and I've always managed to get them in. Also at the same time I've managed to get longer and thinner (penis shaped) toys without trouble.

Is there any tips you could provide? I've tried lots of lube but it reaches a point that I feel it hits my prostate and I can't push any further.