FitNesse.
ExceptionsInFitTables [add child]
If something goes wrong when you push the test button, the most likely cause is that you haven't specified the classpath. Edit the test page and add a !path directive for every classpath that you want included. See BuildingClassPaths for more information.

Another common problem is a mispelling of the test fixture, or one of the column names. The symptom is an exception appearing in the table cell that contains the mispelling.

Hit the Test button to see what these errors look like.

eg.thisTestFixtureDoesNotExist
just some data

eg.Division
dividend divisor quotient()
5 1 5

Another odd problem can occurr if the name of the fixture is a WikiWord. If the corresponding wiki page does not exist, then a ? is appended to it. Fit sees this ? and thinks it's part of the classname. Hit the Test button and then look at the table below. You should see a ? in the table at the end of the fixture name. You should also see that ? in the exception report that follows it. Look closely.

somePackage.ClassThatLooksLikeWikiWordButIsntOne[?]
a b c

If you have a problem like this, then what you need to do is surround the name of the fixture in !- and -! (see MarkupLiteralText).
|! -somePackage.ClassThatLooksLikeWikiWordButIsntOne- !|
|a|b|c|

Or you can also use the literal tables like this:
!|somePackage.ClassThatLooksLikeWikiWordButIsntOne|
|a|b|c|

Tip for viewing exceptions in small font
If you have a scroll-wheel mouse, hold the ctrl key and scroll the wheel. It increases/decreases the font size quickly in most browsers.