Forwarded calls don't go to voice mail

[D3]

First post and question so I apologize for any errors. We are using the inter-tel system with 8500 series of phones. When someone transfers a call to someone at another extension, the call just keeps ringing, it never goes to voice mail. Is there any way to fix this so that the person the call was forwarded to will get the call in voice mail if they aren't able to answer? Thanks for any assistance with this.

[DND ON]

There needs to be a forward path to voice mail programmed, and forwarding must be enabled on the station. Did it ever work?

[D3]

Normal calls go to voice mail just fine, just forwarded calls. And there is a forward path to voice mail and forwarding is enabled.

[emueller]

If the call is being 'Transferred' to the second phone, the second phones System forward path should take the call to voice mail. If the call is 'Forwarded' to the second phone, by a manual forward, system forwarding will not touch the call. Manual forwarding always over rides System forwarding.