I think your timer is missing one or more requred parameters. The required parameters for a valid timer are:
Code:
timer <repetitions> <interval/delay> <command>

Example:
Code:
/timer 1 3 echo -a hi
That's a valid timer: it executes once, after 3 seconds. On execution, it will echo the word "hi" to the active window.

And these will all produce the error message you get - because at least one parameter is missing:
Code:
/timer 1 3 
/timer 1 
/timer echo -a hi
/timer 1 echo -a hi

If you have problems in finding the error, show us your current code. smile