Is it possible to have a shared Ajv schema?

I edited my schema like normal in a request’s Tests. Ran it and it appeared to work correctly.

I cut/pasted the schema to a Collection variable with the name ttSchema. Updated my request test with

var Ajv = require('ajv'),
ajv = new Ajv({logger: console, allErrors: true, verbose: true}),
schema = pm.variables.get("ttSchema");

pm.test('Schema is valid', function() {
  pm.expect(ajv.validate(schema, pm.response.json())).to.be.true;
});

And this is the result of running the request

FAIL Schema is valid | Error: no schema with key or ref "{ "type": "object", "properties": { "employee": {...

My whole schema definition is displayed in the above message.

Any advice?