Web3.py – Error When Interacting with Ethereum Smart Contract Using Web3.py

I'm using web3.py to interact with an Ethereum Smart Contract which is:

pragma solidity ^0.4.0;

contract Coin {
    address public minter;
    string public name;
    mapping (address => uint) public balances;

    event Sent(address from, address to, uint amount);

    function Coin() public {
        minter = msg.sender;
        name = 'MyCoin';
    }

    // Create new Tokens
    function mint(address _reciever, uint _amount) public {
        if (msg.sender != minter) return;
        balances[_reciever] += _amount;
    }

    // Send tokens
    function send(address _reciever, uint _amount) public {
        if (balances[msg.sender] < _amount) return;
        balances[msg.sender] -= _amount;
        balances[_reciever] += _amount;
        Sent(msg.sender, _reciever, _amount);
    }

    function getBalance(address _user) public view returns (uint){
        return balances[_user];
    }

    function balances(address _account) public view returns (uint, string) {
        return (balances[_account], name);
    }
}

Compiling, deploying and generating ABI and contract address were successful. Hower, when i try to access to the deployed smart contract using web3.py i got a strange exception when i call the function balances() in the smart contract.

eth_abi.exceptions.InsufficientDataBytes: Tried to read 32 bytes.  Only got 0 bytes

I used geth with a custom genesis block and parity chain dev node, but without any success.

Here is my Python code:

import json
from web3 import Web3, RPCProvider
from web3.contract import ConciseContract
import time

RPC_IP = '127.0.0.1'
RPC_PORT = '8545'

# read the contract informations then convert them into a Python dict
with open('contract_informations.json', 'r') as f:
    data = json.loads(f.read())

ABI = data.get('abi')
CONTARCT_ADDRESS = data.get('contract_address')

w3 = Web3(RPCProvider(RPC_IP, RPC_PORT))

contract_instance = w3.eth.contract(ABI, CONTARCT_ADDRESS, ContractFactoryClass=ConciseContract)

contract_instance.mint('0x00a329c0648769A73afAc7F9381E08FB43dBEA72', 1000, transact={'from': w3.eth.accounts[0]})


print(contract_instance.getBalance('0x00a329c0648769A73afAc7F9381E08FB43dBEA72'))

When i run the Python code there is two exceptions:

web3.exceptions.BadFunctionCallOutput: Could not transact with/call contract function, is contract deployed correctly and chain synced?

and

eth_abi.exceptions.InsufficientDataBytes: Tried to read 32 bytes.  Only got 0 bytes

However, when i deploy the contract using Parity web interface, everything works fine.

Did, web3.py has some limitations or did i miss something ?

Thanks for your answers.