How does one enter a project budget?

Hello,

We have been on Oracle Projects for over a year;  we are on EBS 12.1.3.  Up to this point, we have never entered Project budgets or forecast.  Now our user is wanting to enter Project budgets. 

On a test instance, I navigate to Projects Super User > Budgets.  I query  an existing  project number and select budget type= “Approved Cost Budget”.  When I press the Tab key or click any other field on the Budgets form, PAXBUEBU, I get error message, “An approved cost budget plan type exist for this project.  You can create new versions only for the corresponding plan type.”  By the way, the project# I chose is a billable project type.