boxster top not fitting in frame

[rd400rz]

I ordered a new top plastic rear window for my 98 boxster last fall from ebay tops on line got it for around $400 not sure on brand it did not fit very well it would pop out on the sides when you tried to put the top back up you had to get out of the car and tuck both sides in the channels to make it go down which was tricky to do you almost needed two people to do it ,so after talking with them I think his name was Vick ,they sent me a much better robins top with the plastic window free of charge and also paid my labor to my shop to redo it ,it did fit better but you still have to help it in the grooves or channels on the sides by the windows I noticed the robins top has helper straps to help it go in the channel I also noted it came with a recall sheet saying all the after market tops do not fit very well on the boxster they all have problems ,the stock top on the car that was ripped when I bought the car went in the grove fine I never had a problem whats up with these after market tops not fitting???