Hi,
Pls. check the fields in LSMW recording for Investment order field in Origin tab.ANLA-EAUFN. Make sure that while recording AS01, this field is highlighted and some value is give - so that system can record this field. And in source structure- provide valid name for it. And maintain the mapping from target to source field. Make sure that Asset class scr.layour rule has this field as optional one.
Cheers,