I originally posted this in the wrong category, so reposting in the right place, apologies for the duplication.

This seems like it should be obvious, but I couldn't find anyone else asking about it. This is what I'm trying to achieve:

Q1. How many people are participating? (answer is a numeral)
Q2. How many votes are cast for options:
a) (numerical input)
b) (numerical input)
c) (numerical input)

The total sum of votes cast in Q2 should be no higher than the answer to Q1 (it may be lower as some may not vote).
So in the advanced settings of Q2 I put "{Q1code}" in the Maximum sum value field.
This doesn't seem to work, as it won't let me give any answer to Q2 and the tip says:

if( ! is_empty('') && is_empty( { groups } ), sprintf('The sum must be at least %s', fixnum('')), '')if(is_empty('') && ! is_empty( { groups } ), sprintf('The sum must be at most %s', fixnum( { groups } )), '')if( ! is_empty('') && ('') == ( { groups } ), sprintf('The sum must equal %s', fixnum('')), '')if( ! is_empty('') && ! is_empty( { groups } ) && ('') != ( { groups } ), sprintf('The sum must be between %s and %s', fixnum(''), fixnum( { groups } )), '')

N.B. the code here for Q2 is 'groups'.

What am I getting wrong?

Can you attache a small sample survey containing only those questions?

Hi,
I've created one here: involver.org.uk/ask/index.php/495238?lang=en
I attach the survey structure file:
Thanks for your help.

You can remove the "Maximum sum value" setting and use this for the "Question validation equation":


And, then something like this for the "Question validation tip":

That's great.

All seems to work.

Thanks.