HMACSHA256 hash key generated by C++/CLI is different from java generated hash key

C++/CLI Function    
I am generating Hash key using C++/CLI and Sending Data and Hashkey Over network to Other Application which is Java But Java Application HashKey Generated is different. Any Idea where i am going wrong? 
Thanking in Advance.

   

     char* EncodeData(char* ap_key, char*  ap_sourceData)
         {
            char* lp_data_to_send = NULL;
        	int key_len = strlen(ap_key);
        	
        	String^ lv_data = gcnew String(ap_sourceData);//Getting Data in System String
        	array<Byte>^ lv_main_data	= Encoding::UTF8->GetBytes(lv_data);//Encoding to UTF-8
        
        	array<Byte>^key = gcnew array< Byte >(key_len + 2);
        	Marshal::Copy((IntPtr)ap_key, key, 0, key_len); //Copy key in System Array Byte
        
        	// Initialize the keyed hash object.
        	HMACSHA256^ myhmacsha256 = gcnew HMACSHA256(key);
        
        	// Compute the hash of the input file.
        	array<Byte>^hashValue = myhmacsha256->ComputeHash(lv_main_data);
        	
        	String^ lv_hex_convert = BitConverter::ToString(hashValue)->Replace("-","");	//Converted to Hexadecimal and replacing '-' with ""
        	Console::WriteLine(lv_hex_convert);//Converted Hexadecimal Hashkey
        
               //Converting to Char*
                lp_data_to_send = (char*)(void*)System::Runtime::InteropServices::Marshal::StringToHGlobalAnsi(lv_hex_convert);//Converting again to char* to be send to Calling Function
    
              myhmacsha256->Clear(); //myhmacsha256 clear Instance
              return lp_data_to_send;//Return Char*
        }
    
    
    int main()
                {
                    //Secret Key shared by C++/CLi application and Java Application
                    String ^ lv_key_g = " My Secret Key";
                    char lv_sourceData[] = { "My data" };
    			    char lv_destinationData[512] = { "" };
    			    char* lp_ret = NULL;
    
    			    array<Byte>^secretkey = gcnew array<Byte>(65);
                    //Converting to UTF-8 
    			    secretkey = Encoding::UTF8->GetBytes(lv_key_g);
    
    			    /*Converting to char* */
    
    			    pin_ptr<System::Byte> p = &secretkey[0];
    			    unsigned char* pby = p;
                    //Converting to Char* to send
    			    char* lp_key = reinterpret_cast<char*>(pby);//Converting data to char* 
    
    			    /*End converting to Byte Array*/
    
    			    lp_ret = EncodeData(lp_key, lv_sourceData);//calling Function
                }


JAVA-FUNCTION


                    String key = "My Key";      //Hash Key Shared by Both Application
    				String hashKey = "My Data"; //Data Shared by both Application 
    				Mac sha256_HMAC = null;
    				try {
                        //Creating Instance
    					sha256_HMAC = Mac.getInstance("HmacSHA256");
    				} catch (NoSuchAlgorithmException e) {
    					e.printStackTrace();
    				}
    				SecretKeySpec secret_key = null;
    				try {
                         
    					secret_key = new SecretKeySpec(key.getBytes("UTF-8"), "HmacSHA256");//UTF-8 Secret Key
    				} catch (UnsupportedEncodingException e) {
    					e.printStackTrace();
    				}
    				try {
    					sha256_HMAC.init(secret_key); //Init Secret Key
    				} catch (InvalidKeyException e) {
    					e.printStackTrace();
    				}
    				final byte[] mac_data = sha256_HMAC.doFinal(hashKey.getBytes());  //Get Data in Bytes
    				
    				String result = "";
    				for (final byte element : mac_data){
                    //Using Radix 16 to convert to String
        					result += Integer.toString((element & 0xff) + 0x100, 16).substring(1);//Converting to Hexadecimal
        				}
        				System.out.print(result);//Hashkey Print