enumerateFolder(SiteData)returns NULL on sharepoint 2010?

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SharePoint

Can you please help me to know where i am doing wrong.

SiteData SiteData = new SiteData();
 String sharePointSourceURL = "Documents/Check";
 Holder<Long> enumerateFolderResult = new Holder<Long>();
 Holder<ArrayOfSFPUrl> vUrls = new Holder<ArrayOfSFPUrl>();
 SiteData.getSiteDataSoap().enumerateFolder(sharePointSourceURL, enumerateFolderResult, vUrls);

 System.out.println(enumerateFolderResult.value);
 System.out.println(vUrls.value);
 if(null != vUrls.value){
  for(SFPUrl url : vUrls.value.getSFPUrl()){
 System.out.println(url.getUrl());
 System.out.println(url.getLastModified());
 System.out.println(url.isIsFolder());
  }
 }else{
  System.out.println("Folder is empty");
 }

Documents/Check :- is the folder that has all the files.
But it is always returing NULL