This generally works fine, except even with exactly the example as above
cut and paste to my templates directory, so it's on the local problems set,
when I try the problem, (click "try it") and then click the "check answers" button, I get a message:
cd /opt/webwork/webwork2/tmp/ImageGenerator.XwevWkbH && /usr/bin/latex equation > latex.out 2> latex.err failed to generate a DVI file at /opt/webwork/pg/lib/WeBWorK/PG/ImageGenerator.pm line 356.
cd /opt/webwork/webwork2/tmp/ImageGenerator.XwevWkbH && /usr/bin/dvipng -bgTransparent -D120 -q -depth equation > dvipng.out 2> dvipng.err returned non-zero status 256: No such file or directory at /opt/webwork/pg/lib/WeBWorK/PG/ImageGenerator.pm line 362.