LM 3886 getting -22V at speaker output

I assemble LM3886 Amp using PCB of circuit basics project i make 3 board and 3 boards are getting -21 volts at speaker output i don't understand what's is going wrong.
without connecting speaker board not taking any current but only showing -21 volt .
If I open mute circuit diode then no -21 volt showing at output .
What is wrong ??
 
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