JOGL - updating vertex coordinates - glMapBuffer always returns null

Question

I want to change vertex positions when key pressed. I use glMapBuffer to get buffer, but it always returns null. This is the code:

Creating vertex buffer:

    FloatBuffer verticesBuffer = FloatBuffer.allocate(vertices.length * 8);
    for (int i = 0; i < vertices.length; i++) {
        verticesBuffer.put(vertices[i].position.x);
        verticesBuffer.put(vertices[i].position.y);
        verticesBuffer.put(vertices[i].position.z);

        verticesBuffer.put(vertices[i].texCoord.x);
        verticesBuffer.put(vertices[i].texCoord.y);

        verticesBuffer.put(vertices[i].normal.x);
        verticesBuffer.put(vertices[i].normal.y);
        verticesBuffer.put(vertices[i].normal.z);

    }
    verticesBuffer.flip();
    gl.glGenBuffers(1, VBOVertices, 0);
    gl.glBindBuffer(gl.GL_ARRAY_BUFFER, VBOVertices[0]);
    gl.glBufferData(gl.GL_ARRAY_BUFFER, verticesBuffer.capacity() * 4, verticesBuffer, gl.GL_DYNAMIC_DRAW);

Getting the buffer:

    gl.glBindBuffer(gl.GL_ARRAY_BUFFER, VBOVertices[0]);
    ByteBuffer verticesByteBuffer = gl.glMapBuffer(gl.GL_ARRAY_BUFFER, gl.GL_WRITE_ONLY); //this is always null
    gl.glUnmapBuffer(gl.GL_ARRAY_BUFFER);