private String checkHashMap(QueryResult other) {
		HashMap<String,Integer> otherMap = other.resultHash;
		String error=null;
		int missing=0;
		int tooMany=0;
		Set<Map.Entry<String, Integer>> keys = otherMap.entrySet();
		Iterator<Map.Entry<String, Integer>> it = keys.iterator();
		
		while(it.hasNext()) {
			String key = it.next().getKey();
			Integer countO = otherMap.get(key);
			
			if(resultHash.containsKey(key)) {
				int count = resultHash.get(key);
				if(count<countO)
					missing += countO - count;
				else if(count>countO)
					tooMany += count - countO;
				resultHash.remove(key);
			}
			else {
				missing += countO;
			}

			tooMany += nrResults - tooMany - other.nrResults + missing ;
		}
		
		if(missing>0)
			error = addError(error, missing + " results are missing. ");
		
		if(tooMany>0)
			error = addError(error, tooMany + " results are incorrect.\n");
		
		return error;
	}