Disability Date & Date Learned fields optional in infotype 0077

Hi,

I need to make  Disability Date and Date Learned fields optional In infotype 0077(Additional personnel data) if i select disability check box.

I have tried using v_T588M to make these fields optional but if i checked  disability check box and these fields are required fields.

if i am not checking the disability check box and these fields are optional only.

Please help me out to make these two fields optional if i checked the disability check box.

Thanks,

Chandu