if-end statement along with Extended function in rtf

Hi Experts,

I have a requirement in rtf template to display a tag based on substring of another tag something like this:

<?if:condition?>EMPLOYEE_NUMBER<?end if?>

condition  = substr(TRANSFORMED_VALUES,1,5)!=''

I have tried as <?xdofx:if substr(TRANSFORMED_VALUES,1,5)!=''?>EMPLOYEE_NUMBER<?end if?>, but the expected output is not printing instead it prints all the employees list.

Much appreciated if somebody can find issue with the usage or let me know the correct usage.

Thanks,

Tarun