Trying If else condition in EVAL in imacros gives error

This is the link from where I m extracting data

TAG POS=1 TYPE=DIV ATTR=CLASS:sLB&&TXT:* EXTRACT=TXT
SET pqr 
SET !EXTRACT NULL
TAG POS=R1 TYPE=INPUT ATTR=TYPE:HIDDEN&&TXT:* EXTRACT=TXT
SET abc 
SET !EXTRACT NULL
TAG POS=R1 TYPE=INPUT ATTR=TYPE:HIDDEN&&TXT:* EXTRACT=TXT
SET def 
SET !EXTRACT NULL
PROMPT " BHK "

SET VAR7 EVAL("if (\"\" == ' ') PROMPT " "; else \"PROMPT " BHK \";")
PROMPT 

Here I'm checking the condition if the value of the variable abc is null or blank, then print data of two variable i.e abc and def else print data of abc and def concatenated with BHK in between the both. But this gives me error

MacroSyntaxError: wrong format of SET command, line 71 (Error code: -910)

Any suggestion where I'm going wrong. Any help would be much appreciated. Thanks