Troubleshooting for DNA extraction from soil (DNeasy powersoil pro kit)d

Greetings, this is a graduated student trying to extract DNA from soil to research soil microbial community. However, despite I followed all of protocols of kit without any change or mistake, the yield of DNA (A260/A280) analyzed low values and graph isn't drawed.

I trying to find out other ways to extract DNA, but is there any reason why DNA isn't extracted well or the way to increase extracted DNA?