Burning Roms help!!!

New to the forum and have been reading a few posts on burning the ROMS downloaded from this site, But I cant seem to find the answers to my issues.
I have a PS2 with a Matrix Infinity Chip fitted, It runs PS1 CDr's without any issues, I have also just created an image from an ORIGINAL GAME using Imageburn. That created a Bin/Cue file. I then burned it with Imageburn and it works great.

However I download some ISO's from here and find them in 7Z files. which I use 7z to unzip, which leaves me with two files, again a Bin/Cue file.
I then load the Cue file into Imageburn, then burn the disc. BUT the disc doesnt work in my PS1. (its the same media as the working one mentioned above)

The only thing my untrained eyes notice is that when I use imageburn to create a bin/cue file from my original PS1 disc, the CUE file is labelled differently as "Disc Image File". as per the picture below.

Can anyone offer any advice on what I am doing wrong....

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