I am using user() function in portal report expression editor with format type o

I am using user() function in portal report expression editor with format type of "Text", but no output is generated. when I use the process variable with formatted type of user name, it is display the user first and last name? when i used the custom rule, which will do the same i.e. user first name and last name concatenation with format of text, no out put is generating.

Any idea about this issue? what are the functions is supported in portal report expression editor?

OriginalPostID-159402

OriginalPostID-159402