my calculation looks like this

0001 >complement= 1110 > adding 0001 = 1111

finally adding it to

0000

1 1 1 1

-------

1 1 1 1 which is wrong

but in reverse i get correct answer

0000 >complement= 1111 > adding 0001 = 0000

0000

0001

-------

0001 which is correct