SY-SUBRC EQ 1001 in Call Transaction of BDC Program

When we run

Mode "N":

Processing without display of screens. If a breakpoint is reached in one of the called transactions, processing is terminated with sy-subrc same as 1001. The field sy-msgty contains "S", sy-msgid contains "00", sy-msgno contains "344", sy-msgv1 contains "SAPMSSY3", and sy-msgv2 contains "0131".

BDC in background then the success subrc is 1001, there is nothing wrong with your code.

If the BDC is runned in background or display error mode the subrc is 1001 whereas for foreground it is 0.