showtip error

[com2]

I have a menu definition file that works fine, but once I add:

;onfunction=showtip('Whatever text');

I get the following error:

Line: 17
Char: 5697
Error: Object expected
Code: 0
URL: http://localhost/

Could someone explain what I do wrong?

[com2]

I already found the error: I forgot to include tooltips.js module.