org.apache.avro.SchemaParseException: Can't redefine:

I'm using data stored in avro-1.7.4 format and trying to use Pig for data manipulation. When trying to LOAD data and then STORE them again I've receive following error:
ERROR 2116: Output Location Validation Failed for: 'file:///home/pig/100/test.avro More info to follow: Can't redefine: Employees
Any ideas / suggestions would be appreciated.
Thanks.
Martin Repka