Resource is required error while calling pa_budget_pub.create_draft_budget

Hello

I have a requirement to create Revenue budget, cost budget and cost forecast on an project...as a first step I am I am trying to create new working revenue budget on the project and I am using pa_budget_pub.create_draft_budget  API. I am seeing in the project on existing Revenue budget version and they are all created at the Top Task Level (like 01,02 etc) no resources. But when I call API it is erroring out with Resource Information is Required. Can anybody please help?

DECLARE

-- variables needed for API standard parameters

   l_api_version_number        NUMBER         := 1.0;