How to use TestCase object in Json payload request?

Hi,
i'm using soapui and i want to know if it is possible to use an object from Custom Properties of TestCase in a json request.

The TestCase Custom proerties object is:
Name=id and Value = 200

The Json request payload is:

{"rep":100,
"email1":[],
"rep":100,
"email2":[],
"rep":100,
"email3":[]
}

If i try this

{"rep":${#TestCase#id},
"recipient1":[],
"rep":${#TestCase#id},
"recipient2":[],
"rep":${#TestCase#id},
"recipient3":[]
}

it says $ is unknown

Thank you for your help