How to write a nested if condition

[abc_18]

Hi,

I have to write a if condition expression in front end. 

Currently my expression for 'Contract' dimension is :-

if([End date] > '$(vDynamicenddate)' or isnull(End date),'Contract','out of scope')

I have to add another condition in this same expression where

Contract end date < '$(vDynamicenddate)','Contract','out of scope')

so both condition should fill for this 'Contract' dimension:-

if [End date] > [Period end date] and Contract end date < [Period end date]  here vDynamicenddate='Period end date'

I tried to write the expression but it's not working as expected, please help