We have a (non-OPL) problem on the product rule, which seems simple enough, but something is not working correctly.

If I try submitting an answer, it gets marked as correct or incorrect, but the message doesn't show up in the results table:

I haven't been able to reproduce it, but one of my students reported the following error:

DBD::mysql::st execute failed: Data too long for column 'frozen_hash' at row 1 at /opt/webwork/webwork2/lib/WeBWorK/DB/Schema/NewSQL/Std.pm line 837.Here is the code for the problem:

## DESCRIPTION

## This is Problem 2.4.15 from the APEX Calculus text. It covers differentiation of basic trig functions and the product rule.

## ENDDESCRIPTION

## DBsubject(Calculus - single variable)

## DBchapter(Differentiation)

## DBsection(Product rule (with trigonometric functions))

## Level(2)

## Institution('Valdosta State University')

## Author('S. V. Ault')

## RevisedBy('F. J. Francis')

## TitleText1('APEX Calculus')

## AuthorText1('Hartman')

## EditionText1('3.0')

## Section1('2.4')

## Problem1('15')

## MO(1)

## Keywords('derivative', 'product rule', 'trig functions', 'ULETH-MATH1560', 'ULETH-MATH1565')

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

# Initialization

DOCUMENT();

# Load whatever macros you need for the problem

loadMacros(

# REQUIRED: Used for basic question and answer operations.

"PGstandard.pl",

# REQUIRED: Used for expression parsing.

"MathObjects.pl",

# Usually required for proper text formatting.

"PGML.pl",

# Used to provide contextual help for how to type inequalities/intervals.

"AnswerFormatHelp.pl"

);

# Sets up basic problem information.

TEXT(beginproblem());

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

# Setup

#-ULETH-#

Context("Numeric");

$a = random(2,9,1);

$f = Formula("x^{$a}");

$fp = $f->D('x');

$r = random(1,2,1);

if ($r==1) {

$g = Formula("sin(x)");

$gp = Formula("cos(x)");

$ans = Formula("$f*cos(x) + $fp*sin(x)")->reduce();

} else {

$g = Formula("cos(x)");

$gp = Formula("-sin(x)");

$ans = Formula("-$f*sin(x) + $fp*cos(x)")->reduce();

}

$fb = Formula($f*$gp)->reduce();

$gb = Formula($fp*$g)->reduce();

#-ENDULETH-#

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

# Problem Text

#-ULETH-#

BEGIN_PGML

Compute the derivative of the given function.

>>[``f(x) = [$f*$g].``]<<

[`f'(x) = `] [_______________] [@ AnswerFormatHelp("formulas") @]*

END_PGML

#-ENDULETH-#

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

# Solution

#-ULETH-#

BEGIN_PGML_SOLUTION

Use the Product Rule.

[``

f'(x) = ([$f])([$gp]) + ([$fp])([$g]) = [$fb] + [$gb] = [$ans].

``]

END_PGML_SOLUTION

#-ENDULETH-#

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

# Answer evaluation

#-ULETH-#

# Setting this to 1 means that students will receive feedback on whether their

# answers are correct.

$showPartialCorrectAnswers = 0;

#-ENDULETH#

ANS( $ans->cmp() );

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

# Comments

COMMENT('

Randomization provides 16 different possible versions of this question.<BR>

Includes a solution set.<BR>

Made from a ULETH template.<BR>

');

ENDDOCUMENT();