Because maybe your indice buffer is your vertex buffer and you do not have a vertex possition buffer just a indice index buffer with vertice indices.
You need two buffers, probally why they are the same because you are looking at the same buffer maybe. Where are you getting your data from inside the buffer. The manechine mesh ?
From what I see you are missing the PossitionVertexBuffer and it’s pointer address, you got a sintax with it inside your loop but you first need to declare that with a pointer address to load buffer into memory.