Custom IF - Zoho Analytics

Custom IF - Zoho Analytics

I am trying to get a formula that returns a negative number if a field is marked with a certain value.

Otherwise it gives the positive value.

Whatever I try, I'm only getting a positive return ... 

This is the formula I'm using - whereby if policy status = lapsed, the return is negative - otherwise it is positive.

If_case("Policy Status",'Lapsed',
'("PC (£) Lapse Reserve" *-1)',
["PC (£) Lapse Reserve"])

Can anyone tell what I am doing wrong? Thanks in advance 

James