Location Script Problems

I am trying to create a script that runs Before Submit on all sales orders placed on our websites that populates the location field on the sales order.  Here is my script but it is not working:

var msgsource = nlapiGetFieldValue('source');    if(msgsource == "Website A")  {   nlapiSetFieldValue('location', 6);  }  else if(msgsource == "Website B")  {   nlapiSetFieldValue('location', 1);  }  else  {   return false;  }  return true;

I do not receive an error for this code but the location field is not being populated after sales orders are created on the webstore.  This is my first script deployment and I am probably doing something wrong.

Also, I am not sure how to debug this type of script.  Usually I throw in an alert message to help me find the problem but I cannot do this here.