Using Dell Cast Dongle with Dell Venue 8 7840 Tablet

I got a very good deal on Dell Cast and I thought I would be able to screencast my tablet contents on my TV. It appears that only the picture can be mirrored on the TV and sound disappears from both the tablet and the TV? 

Can someone confirm that Dell Cast can only mirror the picture on a TV or a monitor and sound is silenced from both the TV and the tablet? Is there any way to project both sound and picture using Dell Cast?

Thanks in advance for your assistance.