IIF condition in table text list

Hi,

I am having a table with text list columns.

I have the below expression used on text list column.

@@IIF(Data.Root.ActiveChannelGroup.Channels.Exists("Ch1") ,Data.Root.ActiveChannelGroup.Channels("Ch1").values(1),"NA")

When the conditions satisfies, it gives the value. But when condition fails, instead of "NA", I am getting empty cell.

I am not sure what's wrong with the syntax. please guide me.