Mirror and DAE exporting

Hi, i think I’ve read all the mirror posts but still could not find a solution … i’ve dup’d, mirrored, recalced normals a design (4 parts) … that looks and works fine and i can change both objects or parts of them … however, when i export the dup’d one (or both at the same time) and import it in second life, the dup’d one is not mirrored at all but like the original except for the spatial positioning of the parts … looking into the DAE, the mirror is not really effectuated but still a -1 reflection … only when i join all objects or parts, the import in SL looks fine but now i cannot separate the objects or parts anymore so that is no option … having said that, i tried with a fake part (added a cube, joined it to a part and removed the vertices again) but that didn’t help … What is it? My wrong? DAE export/import bug?
Any help appreciated … tnx

Update : ctl-A (apply scale) obviously does the trick