execute a command line erase the % char... but i need it

Hello,

i use a script to send After Effect render on a Backburner render farm (an Autodesk product who can launch command line apps like aerender).

This script works well but i need to add some parameters for Backburner. Theses parameters are %tp2 and %tp3.

When i write my script to create a .bet file, the command line is Ok, i can copy it and paste it in a DOS windows and it works.

But when a write my script to directly execute the command line, the % char and all that is between theses chars is simply deleted.

I've tried to add a \ before the % (maybe like a special char) but it doesn't works...

Here is a part of the cript :

var exe_BackburnerSubmit =new File("Submit_To_Backburner.bat");
                exe_BackburnerSubmit.open("w");
                // Text to generate submitted file
                exe_BackburnerSubmit.writeln("path " + '"' + DefaultcmdjobPath + '"'); //Set the path for backburner
                exe_BackburnerSubmit.writeln("cmdjob -jobName " + '"' + JobName + '"' + DefaultAErenderpath + "\\aerender.exe\" -project " + '"' + ProjectFileName + '"' + " -comp " + '"' + CompName + '"' + " -s %tp2 -e %tp3"+ " " + AE_Parameters);
        exe_BackburnerSubmit.writeln("pause");
        
                exe_BackburnerSubmit.close();
                // run it
                exe_BackburnerSubmit.execute("");

Thank you for your help