Save a .step by tdf_label but wrong location

I got a assembly .step file and i want save a part of them.
My code:

void GetAssemblyShapes(const TDF_Label& label, std::vector& vecAssemblyShapes,Handle(XCAFDoc_ShapeTool) aShapeTool){
if (XCAFDoc_ShapeTool::IsAssembly(label)) {
for (const TDF_Label& child : shapeComponents(label,aShapeTool))
GetAssemblyShapes(child, vecAssemblyShapes,aShapeTool);
}
else if (XCAFDoc_ShapeTool::IsReference(label)) {
TDF_Label referred;
XCAFDoc_ShapeTool::GetReferredShape(label, referred);
if(XCAFDoc_ShapeTool::IsAssembly(referred)){
TDF_LabelSequence atestLabels;
XCAFDoc_ShapeTool::GetComponents(referred,atestLabels);
for (TDF_LabelSequence::Iterator cRootIter(atestLabels); cRootIter.More(); cRootIter.Next())
{
GetAssemblyShapes(cRootIter.Value(), vecAssemblyShapes,aShapeTool);
}
}
}


Handle(TDocStd_Document) ok = ReadSTEPToDocument(fileloc);
Handle(XCAFDoc_ShapeTool) aShapeTool = XCAFDoc_DocumentTool::ShapeTool(ok->Main());
TDF_LabelSequence aRootLabels;
aShapeTool→GetFreeShapes(aRootLabels);
std::vector vecShapelabels;
GetAssemblyShapes(aRootLabel, vecShapelabels,aShapeTool);

STEPCAFControl_Writer mywriter;
mywriter.SetColorMode(true);
mywriter.Transfer(alabel);

When i use XCAFDoc_ShapeTool::GetComponents(referred,atestLabels); and save them to .step.I get wrong location part,i want to know how to save right when the label IsReference.