DTExec returns Package path refers to an object that cannot be found

I have an SSIS package and I am trying to execute it using DTExec.exe

My command is like this:

DTExec /F \\SERVERNAME\CUBEDAILYBACKUP.DTSX /MAXCONCURRENT "-1" /CHECKPOINTING OFF /REPORTING EWCPI /CONSOLELOG SMT /SET \PACKAGE.VARIABLES[BackupPath].VALUE;\\SERVERNAME\CUBESBACKUP

      

        
        
        
      

    

and I get the error:

.... The package path refers to an object that cannot be found: "\ PACKAGE.VARIABLES [BackupPath] .value". This happens when an attempt is made to resolve a package path to an object that cannot be found ...