How to get the value of a custom attribute in RTC 3.0.1.3

Hi ,

I'm using RTC 3.0.1.3. How can I get the value of a custom attribute?

I followed the tutorial on the wiki https://jazz.net/wiki/bin/view/Main/AttributeCustomization, but I'm getting an error.

I added the parameter in the Process Configuration Source

<parameters crNumberId="cr"/> // cr is the attribute id

And used the following script to get the value of the custom attribute:

var crId = configuration.getChild("parameters").getStringDefault("crNumberId", "");
       
return workItem.getValue(crId);


I got the following error:

Error executing script myfilename.js

Thanks!
Alicia