Check if both the wires in the smaller speakers are properly connected .. check if the colors red and black are going into the red and black slots respectively and the open wire is pushed all the way inside.
If your wireless receiver is showing a steady blue light when you turn on your soundbar then you should be receiving sound on both your left and right speakers. Another issue to check if you pushed the connections in the wireless receiver all the way in until it makes a click sound.
Hope this helps you sort it out and you can get to enjoying the surround sound experience !