The 4D documentation specifies that the 4DIF tag syntax requires the use of parentheses, for example:

<!--#4DIF (someVar=True)-->

The 4DIF tag will work without the parentheses, but since the syntax calls for using the parentheses, you should always use them. Moreover, the 4D for Dreamweaver plug-in does require the parentheses to correctly parse the 4DIF tag's conditional.

It is very important that you include a space character between the 4DIF and the first parenthesis. If you exclude the space, for example:

<!--#4DIF(someVar=True)-->

the 4DIF will not be correctly evaluated.