Unit no cannot be converted to ST for product 34677"

hi

after snp run when i see /SAPAPO/OPTEXP i find this recurring error many number of times "" Unit no cannot be converted to ST for product 34677" my understanding is that the run is wanting to convert from one unit to another ,and hence it is throwing the error...can you help with any documents that gives clarity on this specific error..i searched all over google i couldnt find any ..