Disappeared bands after the addition of Sigma P2714 - (Sep/06/2013 )

Hey  I am kinda new in proteomics things and I need a whole lot of help here...

the thing is ... we are now trying to extract proteins specific ta target mango var.  using SDS-PAGE, we are using the acetone precipitation method to extract our proteins. Before we add Protease inhibitor mix we had a lot of bands that appeared but in the next runs after the addition of the inhibitor we had an ultra clear GEL! Zero Bands!  How should we USE the Protease inhibtor mix? 

protease inhibitors should be introduced with the medium used for extraction and continued in all subsequent media until the protein of interest is purified.