SAP Message WE110 - The interval & is not external

Diagnosis
You have tried to specify an EAN or a UPC for a number range intervalthat is defined as an external interval. The error lies in theparameters set in Customizing. The likely cause is that an interval hasbeen assigned to a number category as an internal interval, although itis defined as an external interval for the number range object.

Procedure
Get your system(s) administrator to correct the error.