Need Payload sample for action/runScenarioProcessor API

I'm trying to POST an action to Roll up the cost in one scenario… but using the payload below throws me errors. Do you have any ideas?

API

/fscmRestApi/resources/11.13.18.05/costScenariosV2/{ScenarioId}/action/runScenarioProcessor

Payload
{    "scenarioEventType":"ROLLUP"    }

Error

The process scenarioEventType wasn't submitted because of an error. Contact your help desk. (FND-1)