Full Text Search does not return expected results on production server

Hi

I have a FullTextSQLQuery which I am trying to search a phrase(The Multi-part identifier) on full text indexed table. I am getting expected results on running the below sql query on QA machine and PreProduction servers, but not getting the same results on our development and production servres as even though same code running.

SELECT DISTINCT TOP 50 c.case_id,c.status_id,cal.cas_details                       
FROM g_case_action_log cal (READUNCOMMITTED)                      
INNER JOIN g_case c (READUNCOMMITTED) ON (cal.case_id = c.case_id)
INNER JOIN CONTAINSTABLE(es.g_case_action_log, cas_details,
' "The multi-part identifier" OR "<br>The multi-part identifier" OR"The multi-part identifier<br>" ') as key_tbl 
ON cal.log_id = key_tbl.[key] 
ORDER By c.case_id DESC

We are using SqlServer 2008 R2 version on all servers.

Has anyone got any tips to resolve the issue.

Thanks.

kkprasad