Putting if condition in RDLC report

i am using RDLC reports in asp.net c#, i am using expressions like IIF conditions etc, i have used this condition

=iif(Fields!TimeFrame.Value <= 24 AND Fields!TimeFrame.Value >=0 , "Yes", "No")

it works but i just want to handle one another condition what if value returned is =-1 then ?

i want to put condition like if Value= -1 then "Not Yet Received" but it doesn't work like the way i am thinking, help in putting condition,

how to put another

if condition