A PA-28 FILED A FLT PLAN FROM CHEBOYGAN; MI; TO 08C; BUT GRB FSS UNDERSTOOD SHEBOYGAN; WI. ZAU WAS LOOKING FOR WHAT THEY THOUGHT WAS A MISSING ACFT OVER LAKE MICHIGAN.

Narrative

I PLTED A PA28 FROM GRR TO SLH. I COMPLETED THE MISSION WITHOUT INCIDENT; DEPLANED THE 2 PAX; AND THEN TELEPHONED GREEN BAY FSS FOR A WX UPDATE AND TO FILE AN IFR FLT PLAN FOR THE RETURN FROM SLH TO RIVERVIEW ARPT (08C). I TAXIED TO RWY 9 FOR DEP; WE TELEPHONED GREEN BAY FSS ON CELLULAR TELEPHONE FOR OUR DEP CLRNC; CONFIRMING THAT WE WERE READY FOR DEP ON CHEBOYGAN RWY 9. I RECEIVED A DEP CLRNC 'AS FILED' TO CLB AND MAINTAIN 3000 FT; TO EXPECT HIGHER; AND TO CONTACT ZAU. UPON DEP; OUR REPEATED CALLS TO ZAU WENT UNANSWERED. WE THEN TRIED CONTACTING ZMP; THE CTR WITH WHOM WE WERE IN COMS ON THE WAY IN TO SLH SHORTLY BEFORE; AND INFORMED THEM OF OUR INABILITY TO CONTACT ZAU; THAT WE WERE AIRBORNE AND SQUAWKING THE APPROPRIATE XPONDER CODE; WERE AT AND WERE REMAINING AT 3000 FT MSL; WERE IN VMC AT THAT ALT; BUT WOULD ENTER IMC IF WE CLBED. THEY SAID THAT THEY DID NOT HAVE A STRIP ON US; AND THAT THE ERROR WOULD BE WITH FSS; AND TO CONTACT THEM. WE MADE REPEATED ATTEMPTS TO DO SO ON ALL OF THESE FREQS; IDENTING OUR LOCATION AS SLH; BUT RECEIVED NO REPLIES. LANSING FSS CAME UP ASKING IF THEY COULD BE OF ASSISTANCE. WE INFORMED THEM OF OUR DILEMMA -- THEY TOO INDICATED THAT THEY HAD NOTHING ON OUR FLT; BUT THAT WE COULD FILE FROM OUR PRESENT POS AND THEY WOULD IMMEDIATELY FORWARD IT TO ZMP. THIS WE DID. ENRTE; WE MADE A WX DIVERSION TO LDM; CANCELLED IFR; LANDED AND REFUELED. WHILE ON THE GND; MY COMPANION; A CFII; RECEIVED A CALL FROM ZAU MGR WHO STATED THAT THEY WERE LOOKING FOR US; HAD 'LOST US OVER THE LAKE;' AND THAT OUR FLT PLAN WAS STILL OPEN. HE WAS TOLD THE SITUATION WE ENCOUNTERED UPON OUR DEP FROM SLH. I MADE A CALL TO LANSING FSS TO FILE FOR THE REMAINDER OF OUR FLT BACK TO 08C WHICH WE FLEW WITHOUT INCIDENT. AFTER LNDG; WE TRIED TO ASCERTAIN WHAT MIGHT HAVE HAPPENED. AFTER DISCUSSION WITH OTHERS; WE SURMISE THE FOLLOWING: GREEN BAY FSS HAS WITHIN ITS AREA 2 CITIES IN DIFFERENT STATES WITH SIMILAR NAMES: CHEBOYGAN; MICHIGAN (SLH) -- THE ARPT WE WERE USING; AND ONE IN SHEBOYGAN; WI (SBM) OF WHICH WE WERE UNAWARE. THE FSS TECH HAD CONFUSED THE TWO. EVEN THOUGH WE INDICATED THAT WE WOULD BE DEPARTING ON RWY 9 IN CHEBOYGAN; AND DESPITE THE FACT THAT SHEBOYGAN; WISCONSIN; HAS NO SUCH RWY; HE MUST HAVE CONTINUED TO CONFUSE THE 2 ARPTS AND OBTAINED CLRNC FROM ATC FOR OUR DEP FROM THE WRONG ARPT BUT ONE WITH A SIMILAR NAME; NEVER PICKING UP ON THE REPEATED ERROR THEY MADE AT THE TIME WE FILED NOR NOTICING THE DIFFERENCE IN THE RWY CONFIGNS -- WE COULD NOT DEPART FROM SHEBOYGAN; WI (SBM) ON RWY 9 AS THEY HAVE NO SUCH RWY.