Pause/play button greyed out on iPad when playing local files at iPhone

[grumpa]

Hi!

When playing music at one iOS device, you are able to control when to skip/replay/pause/play a song from another iOS device (which is awesome btw). But as the title says, when my iPhone 4 (connected to a dock stereo) plays music I am not able to control when to pause a song from my iPad, if that song:

  - is a local file on my iPhone AND

  - it's not a local file on the iPad.

In other words, if I have a local file on both iDevices, there's no problem. But when there's a problem, being unable to pause the song is not the only one, I'm also unable to see the elapsed time/time progress of the current song, i.e. it doesn't update itself.

This is a new phenomenon with the latest Spotify version 1.9 for iPad, since I never had any problems with this before. 

Regards