Very simple After Effects expression returns ‘undefined value used in expression’ error

Somehow this tried and true expression doesn’t work for me anymore.

I’m using it on the position of a Null but it returns an error on the first line that states ‘undefined value used in expression’:

x = time * 66;

What am I doing wrong? Expressions don’t get much simpler than this.


It should be like this

x = time * 66;