Could not open connection to Search Server

I am Getting below error on this search function call-

CSPhraseConstraint phraseConstraint = new CSPhraseConstraint("OverDraft");// working

CSSearchEngine searchEng = client.getSearchEngine();// working

CSIterator csIterator = searchEng.search(workAreas, phraseConstraint); // throwing error

workAreas- is an array object 

we have seperate server where Teamsite and Teamsite Search are setup.

Error-

com.interwoven.cssdk.common.CSException: (Search Server might be down : java.lang.Exception: Could not open connection to Search Server.)

       at com.interwoven.cssdk.sci.search.CSSearchUtil.executeCommand(CSSearchUtil.java:145)

       at com.interwoven.cssdk.sci.search.SearchServiceSciImpl.executeSearchUtilCommand(SearchServiceSciImpl.java:187)

       at com.interwoven.cssdk.sci.search.SearchServiceSciImpl.searchAreas(SearchServiceSciImpl.java:773)

       at com.interwoven.cssdk.search.java.SearchServiceAdapterImpl.searchAreas(SearchServiceAdapterImpl.java:60)

       at com.interwoven.cssdk.search.impl.CSSearchEngineImpl.search(CSSearchEngineImpl.java:334)

       at Report.getSearchResult(Report.java:128)

       at Report.main(Report.java:28)

Root cause:

com.interwoven.cssdk.common.CSException: (Search Server might be down : java.lang.Exception: Could not open connection to Search Server.)

       at com.interwoven.cssdk.sci.search.CSSearchUtil.exec(CSSearchUtil.java:193)

       at com.interwoven.cssdk.sci.search.CSSearchUtil.executeCommand(CSSearchUtil.java:139)

       at com.interwoven.cssdk.sci.search.SearchServiceSciImpl.executeSearchUtilCommand(SearchServiceSciImpl.java:187)

       at com.interwoven.cssdk.sci.search.SearchServiceSciImpl.searchAreas(SearchServiceSciImpl.java:773)

       at com.interwoven.cssdk.search.java.SearchServiceAdapterImpl.searchAreas(SearchServiceAdapterImpl.java:60)

       at com.interwoven.cssdk.search.impl.CSSearchEngineImpl.search(CSSearchEngineImpl.java:334)

       at Report.getSearchResult(Report.java:128)

       at Report.main(Report.java:28)

We have checked all the services at search server (such as teamsite search, connector, connector) , all are running, we are able to do search from teamsite UI.

Here we are using CSSDK API in our custom utility to use the search. we are also able to connect to teamsite server through CSSDK API , and getting the branches, workarea etc.

Any pointer on why its not able to connect to search server?