pay roll wagetype process issue

Hi,

   we have 3 wagetypes 1000,1001,1002.

1000 is Ee salry=50

   1001=-100 some deduction on Ee.

1002=360 Ee other allowans

here 1002 goes to other employer.

   But system calculating 1000+1002-1001=360.

   My requirement is :  system need to do 1000-1001=-50

   And 1002 amount stay same.

Advice me on this issue

Thanks,