Our university recently upgraded to WW3 and it works nicely. Earlier this week, we experienced some issues with a draggable proof problem. If a student submits the same answer twice in a roll, the second answer is recorded as 'empty'. Because of which, the right column disappears. This was not an issue with WW2 and we are not sure how to fix it. Any suggestions? Thank you.

Below is the problem pg file:

DOCUMENT();

loadMacros(

"PGstandard.pl",

"MathObjects.pl",

"PGML.pl",

"PGbasicmacros.pl",

"parserRadioButtons.pl",

"draggableProof.pl",

"PGcourse.pl"

);

TEXT(beginproblem());

###########################

# Setup

Context("Numeric");

$CorrectProof = DraggableProof([

"Let \(n\) be even.",

"By the definition of even, \(n = 2k\) for some integer \(k\).",

"It follows that

\(\\n^2 + 3n + 5 = (2k)^2 + 3(2k) + 5\)

\(\\ \hspace{38mm}= 4k^2 + 6k + 5\)

\(\\ \hspace{37mm} = 2(2k^2 + 3k+ 2) + 1\)",

"Since \(k\) is an integer,",

"\(2k^2 + 3k+ 2\) is an integer.",

"Since \(n^2 + 3n + 5\) equals \(2\) times an integer plus one,",

"\(n^2 + 3n + 5\) is odd."],

["\(2k^2 + 3k+ 2\) is even.",

"By the definition of odd, \(n = 2k + 1\) for some integer \(k\).",

"Let \(n\) be odd."] ,

SourceLabel => "Choose from this list of sentences",

TargetLabel => "Direct proof of the statement (in order):",

);

###################################

# Main text

BEGIN_PGML

Order *[$CorrectProof->numNeeded] of* the following sentences so that they form a direct proof of the statement: If [`n`] is even, then [`n^2 + 3n + 5`] is odd.

[@ $CorrectProof->Print @]*

END_PGML

############################

# Answer evaluation

$showPartialCorrectAnswers = 0;

install_problem_grader(~~&std_problem_grader);

ANS($CorrectProof->cmp);

ENDDOCUMENT();