T46G - uploaded ringtone not enabled

[timalex]

Phones firmware 28.72.0.26.

We put the following in provisioning files:

Code:

ringtone.url = http://myProvisioningServer/yealink/myRingTone.wav
phone_setting.ring_type = myRingTone.wav
account.1.ringtone.ring_type = myRingTone.wav

What happens:
The wav file ist uploaded. Both settings can be seen in phones web.

Problem: New wav will not be enabled, the phone will play Ring1.wav instead.

Manual switching afterwards via web is working, then the phone will use myRingTone.wav as wanted.

Any ideas why this is not working by provisioning as expected?