Mod loading error has occurred

Hello everyone, please, help me. My mod doesn't start because of error. Error are under:

Failure message: EconomicsMod (economicsmod) encountered an error during the common_setup event phase
        java.lang.NullPointerException: Cannot read field "delegate" because "this.sound" is null

I added a sound for music disks, but how can they be a problem for launching mod?