Here, it works well:
(defvar myVar 2 "This is the documentation string") ; C-x C-e
(documentation-property 'myVar 'variable-documentation) ; C-x C-e
--> "This is the documentation string"
Thanks Pascal! You lead me to the error. When I typed (documentation-
property 'some_variable 'variable-documentation) and evaluated it, it
worked. I then compared it to the equivalent part of the message
statement that I was using, and after 15 seconds of looking at it I
realized that I had incorrectly used a dash, instead of an underscore
for the variable name in the documentation-property function call. I
will have to remember to post the exact code I am using and not type
in something equivalent. But I would have expected to have gotten an
error because the symbol-name that I erroneously typed did not exist.
In fact, I would prefer it gave an error to returning nil.