Replace shower door

[wcoloradokid]

Wanted to replace shower enclosure door since it was pretty faded by the sun. Got an exact replacement from Amazon and discovered it just won’t fit, seems it’s slightly too big even though it measures like original, any suggestions? Is it possible that frame may have shifted over time, or shrank? I know this sounds bizarre!
Capt Dave
I have a Rockwood Premier, A Frame

[SeaDog]

I'm having a hard understanding how a door that measures the same as the original worn't fit. could it be that the hinges are installed at different settings on the new door. If so you may be able to reset them.