Not enough information has been provided for us to know why it's "not working". ..."not working" isn't an error message. It's not even a description of a problem. It's just an acknowledgement that there is a disconnect between what you expect and what you get.

Post a minimal code snippet that demonstrates your problem. Post the error message you're getting. Post what output you were expecting, and what output is actually occurring. Then we might be able to answer reasonably well. And chances are that as you work on creating a 10 to 15 line snippet of code to demonstrate to us what's going on, you'll discover the problem along the way yourself.