Error in expression:')' expected

[#1]

I'm trying to loop through a load script.  I'm getting   "Error in expression:')' expected" on the if statement.  I've tried a number of things with no luck. Any ideas?  Thanks.

let sub = $(sub) + 1;

if ($(sub) = 3 or 5 or 7 or 8 or 10 or 12, let $(FromDate) = $(FromDate) + 31,
if ($(sub) = 2, let $(FromDate) = $(FromDate) + 28, $(FromDate) = $(FromDate) + 30));

if ($(sub) = 3 or 5 or 7 or 8 or 10 or 12, let $(ToDate) = $(ToDate) + 31,
if ($(sub) = 2, let $(ToDate) = $(ToDate) + 28, $(ToDate) = $(ToDate) + 30));

loop

[hic · Accepted solution]

You should not use the if-function. Use the IF control statement instead: IF <condition> THEN <statement> END IF.