Problem with mdlLinear_extract

Hi,
using the following code, I had unexpected returned values .
foobar(MSElementDescr* curElm,List lineList) {

  DPoint3d* linePts;
  int numVert =0, elemType;

  elemType = mdlElement_getType (&curElm->el);

  if( LINE_ELM == elemType ) {

      linePts = (DPoint3d*) malloc(2*(sizeof(DPoint3d)));
      memset(linePts, 0, 2*(sizeof(DPoint3d)));
      mdlLinear_extract(linePts,&numVert,&curElm-
>el,mdlModelRef_getActive());
      printf("linePts[0].x=%f\tlinePts[1].x=%f
\n",linePts[0].x,linePts[1].x);
  }

}

Printed values are: linePts[0].x=-1.#QNAN0 and
linePts[1].x=-1235866245348632500000000000000000000000000000
00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000000.000000

What is my error?

I hope you can help me.
Thanks

Biagio