I know this was from a while ago but this fixed the issue I was having of the wrong schema being used when bringing an existing report from one environment to another, which there doesn't seem to be a clear answer for anywhere but here. This was an ideal solution because it removed the schema from the query, which allows us to easily move the report around environments.

For your question, I'm sure you've already solved it but you can duplicate your error by copying your SQL query into a standard SQL Developer interface which will tell you where the problem is more specifically. I'm guessing you may be missing a synonym or something.