ACFT MISID ON RADAR.

Narrative

WE WERE APCHING MSP; FLYING THE STAR (NICKL 2 WITH BRB TRANSITION). WE WERE HDG W. THE CTLR SUDDENLY INSTRUCTED US TO TURN 10 DEGS R AND RE-INTERCEPT THE ARR. WE WERE STARTLED; BECAUSE OUR 2 RNAV DISPLAYS SHOWED US TO BE EXACTLY ON THE ARR. THUS WE COULDN'T COMPLY WITH BOTH PARTS OF THE CTLR'S DIRECTION; SINCE A TURN WOULD TAKE US AWAY FROM THE ARR; AND WE WOULD NEVER RE-INTERCEPT. I ASKED HER WHERE SHE SHOWED OUR POS; AND I TOLD HER WE WERE CONCERNED BECAUSE WE SHOWED ON COURSE WITH OUR COCKPIT DISPLAYS. SHE REPLIED THAT SHE SHOWED US 7 MI N OF COURSE AND REPEATED THE COMMAND TO TURN; THIS TIME WITH IRRITATION. THAT MADE EVEN LESS SENSE; BECAUSE IF WE WERE N OF COURSE AND TURNED R; WE WOULD GET FARTHER AWAY. MEANWHILE WE XCHKED THE RAW VOR DATA; AND IT AGREED WITH THE RNAV. I TOLD HER I WAS CONFUSED ABOUT WHAT SHE WANTED; AND SHE REPLIED THAT WE SHOULD GO DIRECT TO THE NEXT INTXN. SHE WAS BUSY WITH TFC; SO WE DID SO AND SAID NO MORE. PERHAPS SHE THOUGHT WE WERE ARRIVING FROM MKE RATHER THAN GRB. THAT WOULD EXPLAIN THE 7 MI N; BUT A R TURN WOULD STILL BE WRONG. PERHAPS THE CTLR'S MAP IS IN ERROR; FOR I HAVE HEARD CTLRS TELL SEVERAL OTHER ACFT THAT THEY WERE OFF COURSE IN THAT AREA.