LG Vortex Notification sounds help!

[VastCityLights]

I use handcent sms for text messages. I'd like to set a custom tone for when my boyfriend sends me a text. I already have the tone in my phone, and I went in handcent and set that as the tone I'd like to play for him. However, both when I test the notification, and when he actually sends me a text, it still plays the default tone I have set instead of the custom one. I've already disabled text notifications from the stock messaging app...I'm not sure what I've done wrong. Can anybody help me? I've been trying to look up how to fix this for hours, but have found nothing.