Trying to install my new home theatre
Are you sure the wire is not damaged somewhere? Are you sure that you are connecting the wire to the correct terminal on the receiver? Is the speaker OK?
To test all of this, try different combinations. With Right speaker working, disconnect the wire from speaker and connect it to the left speaker. If it doesn't work, then the left speaker is faulty.
Now disconnect the wire from receiver's right-front terminal and connect to left-front terminal. If it doesn't work, you are either connecting to wrong terminal or the terminal/receiver is faulty.
At last, try using the "left" wire to connect the rigth speaker to right terminal. If it doesn't work, the wire is faulty.
P.S. The +/- doesn't matter for testing, the sound should go either. It is just needed to have all speakers connected in the same polarity, because else the sound waves would eliminate themselves.