What is the reason the tape won't play on sa-ak95

It may be the tape(s) themselves. Pre-recorded cassette tapes are usually no problem for most players, but many user-recorded tapes were of the C90 or C120 variety. These cassettes use much thinner tape in order to get the recording time. This can cause the tape, after many starts and stops and partial fast-forwards and rewinds to get tight on the reels. This will cause the tape sensor to think that the tape is at the end of the reel when it is not. Sometimes rewinding from end-to-end will help, but not always,