sendTransaction BigNumber Fehler: new BigNumber() keine Zahl: [object Object]

Ich bin neu in der Solidity-Programmierung und schreibe intelligente Verträge für eine der Anwendungen. Hier sind meine beiden Verträge. Ich verwende truffle und testrpc als Werkzeug. Ich erhalte ständig Fehler. Anleitung brauchen. Ich habe frühere Threads mit ähnlichen Betreffzeilen gesehen, aber sie helfen nicht. Ich habe auch schon versucht, den Namen der Funktion zu ändern.

//Certificate.sol

contract Certificate {
    address private addressSelf;
    bytes32 private certName;

    function Certificate(bytes32 _certName) {
        addressSelf = msg.sender;  
        certName = _certName;
    }  
}

//Participant.sol

contract Participant {
    address private addressSelf;
    bytes32 private participantName;

    struct CertStruct {
        Certificate certificateData;
        bool isCertificate;
    }

    mapping (address => CertStruct) public certStructs;
    mapping (uint => address) public certIndex;
    uint public noOfCerts;

    function Participant(bytes32 _partName) {
        addressSelf = msg.sender;  // just set the self
        participantName = _partName;
        noOfCerts = 0;
    }

    function isCertGranted(address certAddress) public constant returns(bool) {
        return certStructs[certAddress].isCertificate;
    }

    function grantCertToParticipant(address certAddress, Certificate certificate) payable public returns (bool)
    {
        if(!isCertGranted(certAddress)) return false;

        CertStruct memory newCertStruct;
        newCertStruct.certificateData = certificate;
        newCertStruct.isCertificate = true;
        certStructs[certAddress] = newCertStruct;
        certIndex[noOfCerts] = certAddress;
        noOfCerts++;

        return true;
    }
}

//participant.js

var CertificateSol = artifacts.require("./Certificate.sol");

var ParticipantSol = artifacts.require("./Participant.sol");

contract('Participant', function() {

    it("should put certificate in the one participant", function() {

        var newCert;
        var newPart;

        return CertificateSol.new('CertName').then(function(newCertInstance) {
            newCert = newCertInstance;
        }

        return ParticipantSol.new('Name of Participant').then(function(newPartInstance) {
            newPart = newPartInstance;

        newPart.grantCertToParticipant.sendTransaction(newCert.address, newCert, { from : web3.eth.accounts[0], gas: 3000000 }).then(function(returnFlag){

            newPart.noOfCerts.call().then(function(certNumber){
              console.log('certNumber is ' + certNumber.toString(10));
          });
        }).catch(function(err){
          console.log('I am at grantCertToParticipant err ' + err);
        });

    });    
}