Hawai SDK speech to text in windows phone 8

hi, i try create apps, and use speech to text sdk (hawai SDK). In windows phone sdk 7.1 running well. But in windows sdk 8 i got some erorr when running apps in emulator.

An exception of type 'System.Reflection.TargetInvocationException' occurred in mscorlib.ni.dll but was not handled in user code

If there is a handler for this exception, the program may be safely continued.

refer to the error code

// The following try/finally block is needed to avoid CA2202 and CA2000 warnings.
            try
            {
                bool fileExists = (bool)existsMethodInfo.Invoke(null, new object[] { configFilePath });

                if (fileExists)
                {
                    IEnumerable<string> lines = (IEnumerable<string>)readLinesMethodInfo.Invoke(null, new object[] { configFilePath });
                    foreach (string line in lines)
                    {
                        if (!string.IsNullOrEmpty(line))
                        {
                            return line;
                        }
                        else
                        {
                            break;
                        }
                    }
                }

does anyone can help this problem ? regards,