how to use the saveas4 function

Dear all
i am new to the solidworks API...
currently i can draw a cylinder with the dll...and after the drawing i
want to save the part as STL format...
i looked into the API help file and found maybe saveas4 can be used.
but some errors when compiling...
cannot figure out where is the problems
void MenuItemCB(void)
{
LPMODELDOC pModelDoc;//define pModelDoc pointer
TheApplication->GetSWApp()->get_IActiveDoc(&pModelDoc);//obtain
pModelDoc pointer
LPPARTDOC pPartDoc;// define pPartDoc pointer
pModelDoc->QueryInterface(IID_IPartDoc,(LPVOID *)&pPartDoc);//obtain
pPartDoc pointer
VARIANT_BOOL retval;//define retval
pModelDoc->SelectByID(auT("Front"),auT("PLANE"),0,0,0,&retval);
pModelDoc->InsertSketch();//enter sketching drawing
double P1[3];// defind and evaluate p1 & p2
P1[0]=0;
P1[1]=0;
P1[2]=0;
double P2[3];
P2[0]=0;
P2[1]=0.1;
P2[2]=0;
pModelDoc->ICreateCenterLine ( P1, P2 );//draw the center line through
P1, P2
pModelDoc->ClearSelection();//clear selection
LPSKETCHSEGMENT retval2;//define retval2
pModelDoc->ICreateLine2 ( 0, 0, 0, 0.03, 0, 0, &retval2 );//draw line
pModelDoc->ICreateLine2 ( 0.03, 0, 0, 0.03, 0.09, 0, &retval2 );//draw
line
pModelDoc->ICreateLine2 ( 0.03, 0.09, 0, 0, 0.09, 0, &retval2);
pModelDoc->ICreateLine2 ( 0, 0.09, 0, 0, 0, 0, &retval2 );//draw line
pModelDoc->InsertSketch();//quit sketch
VARIANT_BOOL retvala;//define retvala
VARIANT_BOOL retvalb;//define retvalb
VARIANT_BOOL retvalc;//define retvalc
VARIANT_BOOL retvald;//define retvald
VARIANT_BOOL retvale;//define retvale
VARIANT_BOOL retvalf;
pModelDoc->SelectByID(auT("Line2"), auT("SKETCHSEGMENT"),0,
0,0,&retvala);//
pModelDoc->SelectByID(auT("Line3"), auT("SKETCHSEGMENT"),0,
0,0,&retvalb);
pModelDoc->SelectByID(auT("Line4"),
auT("SKETCHSEGMENT"),0,0,0,&retvalc);
pModelDoc->SelectByID(auT("Line5"),
auT("SKETCHSEGMENT"),0,0,0,&retvald);
pModelDoc->SelectByID(auT("Point2"),
auT("SKETCHPOINT"),0,0,0,&retvale); //
pPartDoc->FeatureRevolve (6.28318530718, 0, 0, 0);//
pModelDoc->BlankSketch ( );//
pModelDoc->ShowNamedView2(auT("*Isometric"),7);//
pModelDoc->ViewZoomtofit2();//
////////the above codes are used to draw the cylinder and clear the
sketch
pModelDoc->SaveAs4("Cylinder.stl", swSaveAsCurrentVersion,
swSaveAsOptions_SaveReferenced, &retvalf);
/////this want to be added to save the part as STL format...
but the compiling errors is that error C2039: 'SaveAs4' : is not a
member of 'IModelDoc'
what is the problem?
and also i am not sure if it is right to define the parameters in the
saveas4 as swSaveAsCurrentVersion, swSaveAsOptions_SaveReferenced,
&retvalf);
thanks for all the help