[Yaffs] silly old name

Hello,

i'm new on yaffs and I'm currently testing the robustness.
There I have now the Problem that if I unplug the Device from Power when I write data to a file that the file is then renamed to "silly old name".
Can anyone help me and tell me how this can happen an how I can fix that?

We test yaffs because we have thought that it is robust enough to not loose data when the device is unplugged from Power.

Regards
markus