WsSQL exception processing internal fpos columns

On the 190 cluster, I tried the following query

SELECT state_code, county_fips, county_name,_internal_fpos_ FROM thor_data400::key::fips2county::20110311::fips2county

and received the following error

2015-03-10 19:51:48 GMT: INVALID COLUMN FOUND: thor_data400::key::fips2county::20110311::fips2county.nternal_fpos__

WsSQL correctly reports back the following layout

RECORD
string2 state_code;
string3 county_fips;
string18 county_name;
unsigned8 _internal_fpos_;
END;