find CMOD/SMOD enhancments for infotypes

Hi Experts!

May we know how to we can find CMOD/SMOD enhancments for infotypes. We have a requirement for infotype 0494 where in we need to add a pushbutton on its subscreen. However, once click the pushbutton we applied, an error is showing, saying 'This function is not possible.'

We were thinking this may need an enhancement but we can't seem to find the enhancement components. Please advise.