Hi Armor,
If you could let us know approx what time you experienced these problems, we can check our logs.
One possible explanation is that the Free Sample player is limited to about 10-minutes of playback, and then won't allow any further playback for a period of time. So for example if you allow it to play until it stops, and you immediately try to use it again, it won't work. This is how we expect it to behave.
Also, you can sign-up for iBox, and won't be charged anything for the first month. This would allow you to do a more comprehensive test. If you are still having problems after you sign-up, just email our service department and they will cancel your subscription.
Regarding your Walker Android box, as you can appreciate there are a lot of Android devices on the market, and we are not in a position to test them all with our app. Of the ones we have tested, some of them tend to start the video before the sound (so you might get a few seconds of silent video, before the sound kicks-in). This is down to how the box manufacturer implemented their system, so we don't have any control over it. Might this be happening with the channels you are experiencing no sound on?
By the way, if you are using a d-pad (arrow pad) to navigate the menu on the Walker box (as opposed to using a mouse or touch interface) we can supply you with a special version of the iBox app, that is optimised for d-pad navigation.
Regards.
Rover