Sage X3 ERP v7 Patch 8

I'm trying to figure out how to import Journal Entries to alleviate the time spent by our Accounting Dept. I know the data I'm inputting is accurate because I'm just re-importing data exported from the Production server (excluding the Document Number). When importing this into the Test environment (where this record does not exist), I get the below error message.

As you can see, when I search for this entry it does not appear. The last entry in the Test environment was GEN006298, so GEN006299 is the next available document number. 

Has anyone else experienced this? I've found no resources that address this issue.