String.format expression in C#

Question

Ist expression works for Person Address in string format in my report field, but if there is no Person address, then pull from Location address:

String.Format("{0}, {1}  {2}",
 Fields!PersonCity.Value,
 Fields!PersonStateCode.Value,
 Fields!PersonZipCode.Value)

 

//Modified to add Location address:

String.Format("{0}, {1}  {2}",
 Fields!PersonCity.Value,
 Fields!PersonStateCode.Value,
 Fields!PersonZipCode.Value), IIF(IsNothing(Fields!LocationCity.Value,
 Fields!LocationStateCode.Value,
 Fields!LocationZipCode.Value))

 

I get BC302015 end of statement expected error.