Is Null in Set Analysis

[#1]

Help.   I am just trying to convert the If/Then SUM expression below, that works fine but is slow, to Set Analysis.   I don't know how to get the IsNull to work in Set Analysis despite searching forums.   Seems like this should be a simple modification.  

Can anyone please assist??

Thanks MUCH.

Original If/Then that works fine:

= sum(if(IsNull(TCW) and TCNB=0,TCAmt))


Trying to convert to Set Analysis, have tried this one and many others with no luck.  :

=sum({<TCNB={0}, $(TCW=("")"} TCAmt))

[#2]

Thanks Michael.  I was beginning to come to that conclusion as well.  I will likely still try and determine why the data model and set analysis works perfectly in some of the results but returns blanks in others.  Seems odd but of course there is a reason, just need to find it.  I am sure it has something to do with the key table I have created with Outer Joins.  

In the mean time, will stick with the IF, as I have 'bigger fish to fry' in this dev effort.

Appreciate all the feedback!

[#3]

FYI - I tried this formula in a different element and it worked perfectly.  So marked as correct answer.

THANKS!

[#4]

Hi All, FYI

[Field_name]=e({<[Field_name]={''}>} [Field_name]) - if we want NOT ISNULL ([Field_name])  

[jmatarini2015]

Hi Micheal,

Requesting to help me understand {($ -<TCW={'*'}>) * <TCNB={'0'}>} 

Thanks & Regards,

Das