BPC 11 custom measure

Hi experts,

I need to create a custom measure in order to reverse sign of account based on the value of a dimension, in order to do so i created a property named "SIGN" in my dimension with value 0 or 1.

This is my custom measure's code

'IIF([%C_CODE%].CURRENTMEMBER.PROPERTIES("SIGN")="1",-[MEASURES].[/CPMB/SDATA], IIF([%C_CODE%].CURRENTMEMBER.PROPERTIES("SIGN")="0",[MEASURES].[/CPMB/SDATA]),[MEASURES].[/CPMB/SDATA])))';

But it's not working, it gives me an MDX: internal error

I think that my code is not correct

Do you guys have an idea what it might be ?

Thank you