Test Execute fails in mapping GUI object

public var FindChild(var father, string mapExp, string description) //, int numberOfIteration = 0)
        {
            try
            {
                string[] mapExpArr = Regex.Split(mapExp, "//");
                int numberOfMappedObjects = mapExpArr.Length;

                if (numberOfMappedObjects == 1)
                {
                    return FindChildFromTC(father, mapExp, description);
                }

                father = FindChildFromTC(father, mapExpArr[0], description);
                int indexOfNextFather = mapExp.IndexOf(@"//");
                if (father != null)
                {
                    return FindChild(father, mapExp.Substring(indexOfNextFather + 2), description);
                }
                else
                {
                    return null;
                }
            }
            catch (Exception ex)
            {
                // in case an exception was thrown from TC before VerifySuccessActionInTestComplete and the TC reported an error
                if (!ex.Message.Contains("a Test Complete error was found"))
                {
                    if (int.Parse(Connect.Log["ErrCount"]().UnWrap().ToString()) > _numOfErrorInTc)
                    {
                        _numOfErrorInTc++;
                    }
                }

                foreach (IDriverReportListener reportListener in reportListeners)
                {
                    reportListener.ElementNotFound(description);
                }

                _numOfErrorInTc++; //increasing number of errors by 1 after reporting perform action exception in TC

                //throw new Exception("An exception was thrown while trying to FindChild " + description + " with the mapObjExp " + mapExp);
                ThrowException(ex,
                    "An exception was thrown while trying to FindChild " + description + " with the mapObjExp " + mapExp);
                return null;
            }
        }