It is so cool to be able to enjoy Apple music on iTunes in both Windows and Mac OS X. However, my users have been complaining about they can not play the songs from particular albums on iTunes while the can play any songs of other albums since they logged in to their Apple Music account already. This is the error:
The song cannot be played because you are not signed in to Apple Music. You must be signed in to Apple Music in order to play Apple Music songs.

cannot be played because you are not signed into Apple Music

This error is such the limit of time the tracks can be played during the trial period. And this problem happens under iTunes in both Mac OS X and Windows.

How to fix?

In Windows

You get the boring message of “You must be signed in to Apple Music in order to play Apple Music songs” on the songs cached in your HDD. Removing the SubscriptionPlayCache in the following direction will solve the problem.
C:\Users\[username]\AppData\Local\Apple Computer\iTunes\SubscriptionPlayCache

In Mac OS X

Do the same thing on the corresponding direction in Mac OS X will get rid of ‘The song cannot be played because you are not signed in to Apple Music…’
~/Library/Caches/com.apple.iTunes/SubscriptionPlayCache