Why doesn't all DVD+R media work on DVD+RW burner?

Why doesn’t all DVD+R media work on DVD+RW burner?
I can understand the noncompatibility between DVD-R media on DVD+RW burner and viceversa, but why some DVD+R doesn’t work on DVD+RW player?

All DVD+R media should work with a DVD+R/W drive.

Why don’t you post your drive model, media code, and the specific problem you’re having?

Maybe you have bad dvd+r’s…post more info, as stated above…