glDrawElements, GL_LINES, and duck, very simple stuff!

Hello, I’m back to learning collada, and having problems with infamous duck(at least for me).
Duck model can be found here(model bank): … le_details

What I do is get the vertices array, collect vertex indices from

, shove it in as vertex array and display as GL_LINES, like this

/* sort of load method */
domListOfFloats * position_floats = & source->getFloat_array()->getValue();
// pvertices is an instance variable
pvertices = new GLfloat[position_floats->getCount()];
for (unsigned int i=0; i< position_floats->getCount(); i++) {
	pvertices[i] = (GLfloat)(*position_floats)[i];

and in other method

glVertexPointer(3, GL_FLOAT, 0, [self vertices]);
/* n_vertex_indices are vertex only indices from 

, vertex indices have offset 2, so every third is stored in special array */
glDrawElements(GL_LINES, n_vertex_indices, GL_UNSIGNED_SHORT, vertex_indices);

Duck looks like a duck, but there is something wrong, please look at it … 3680320114

Pretty much all line are crooked and some cross or extend outside the duck…
I’m pretty sure I do something wrong with glDrawElements, I’m quite skeptical I can just draw the duck in on function call. I mean how does it know how to connect lines and such.

Please could someone clarify this for me,
Kind regards