Do you have the mounting kit for it. Most of the older drives used a casing with electrical connectors to mount the drives. Some of the later models of some manufacturers use a connector to change the type of connector to a theoretically more reliable system. If not, most are available online, but usually at exorbitant prices.
I finally got it, it didnt have the caddy it was suppose to have to make it easier. It was difficult to work that new thin frame hard drive into there with no supporting caddy. Be careful too, I slightly bent two of the pins on the connector inside the bay But it works fine so far