c++ - loading 3d model in directx 11 assimp

Question

I'm newcomer in this forum. I'm trying load 3d model im my programm using assimp, but there is some errors occured. There is my code:

bool Model::LoadModel(const char* fileName)
{
Assimp::Importer imp;
const aiScene* pScene = NULL;
const aiMesh* pMesh = NULL;

pScene = imp.ReadFile(fileName, aiProcess_Triangulate);
if(!pScene)
{
    MessageBox(NULL, "Error read file", "Error", MB_OK);
    return false;
}
else
    MessageBox(NULL, "read file OK", "Error", MB_OK);

pMesh = pScene->mMeshes[0];
if(!pMesh)
{
    MessageBox(NULL, "Failed to find meshes", "Error", MB_OK);
    return false;
}

for(unsigned int i = 0; i < pMesh->mNumFaces; i++)
{
    if(pMesh->mFaces[i].mNumIndices == 3)
        numIndices_ = numIndices_ + 3;
    else
    {
        MessageBox(NULL, "Failed to parsing faces", "Error", MB_OK);
        return false;
    }
}

return true;
}

When programm starts execute line pMesh->mFaces[i].mNumIndices == 3, runtime error occurs. Debug log file tell me that is can't calculate mNumIndices. Maybe anyone can help me? I have no idea why this happens.