BDC Error : Field BSEG-FDTAG. is not an input field: Need to press enter explicitly to save data.

BDC session method giving an error "Field BSEG-FDTAG. is not an input field", whenever im trying to upload data using bdc in tcode FB01, its a program of " CTM ". so here data is uploading properly for every posting key (28,50,1,35), but whenever there's come combination of 09 and 19 posting key, its giving error for FDTAG, and one more thing in FB01, field FDTAG and FDLEV in here im not uploading value, its system generated so ive cleared those values(this was the requirement), but now for 9 and 19 combination its not saving the uploaded data., other keys data is saving succesfully, Anyone have any idea regarding this, Ive been stuck in this issue since long. please help.