Invalid watch expression

The specified watch expression isn't a valid expression. This error has the following cause and solution:

• The watch expression is syntactically incorrect.

  Check the syntax of all components in the expression. Note that the syntax for a watch expression corresponds to the locale of the project in which the expression being watched is defined.

For additional information, select the item in question and press F1 (in Windows) or HELP (on the Macintosh).