Hi
pl check the your requirement Class level , it is activate availability and requirement class , it is not activated system will give the error like your error message
this is abap code for error message
IF ( T459K-BEDSD NE SPACE OR T459K-ATPPR NE SPACE ) AND
VBAP-MTVFP IS INITIAL.
IF NEUTERMINIERUNG EQ CHARX.
MESSAGE ID 'VV' TYPE CHARE NUMBER 083 WITH VBAP-VBELN VBAP-POSNR.
ELSE.
MESSAGE ID 'VV' TYPE CHARI NUMBER 083 WITH VBAP-VBELN VBAP-POSNR.
ENDIF.
EXIT.
ENDIF.
check this and confirm
regards
sankar