Change uuid (bios.uuid) of a VM

Hi,

I tried to change the UUID this way:

var UUIDlog = vcVM.config.uuid;
System.log("UUID at the moment: " + UUIDlog);
System.log("UUID to set : " + UUIDnew);
vcVM.config.uuid = UUIDnew;
var UUIDcontrol = vcVM.config.uuid;
System.log("UUID after change: " + UUIDcontrol);

vCO shows the mo correct value but the VMX File isn’t updated.

[2015-01-07 17:05:48.923] [I] UUID at the moment: 564dc846-3c30-b95f-84fc-4d9e168ecd07

[2015-01-07 17:05:48.923] [I] UUID to set : 42286f25-0cfe-4a18-ffd4-79a682663297

[2015-01-07 17:05:48.923] [I] UUID after change: 42286f25-0cfe-4a18-ffd4-79a682663297

Does anybody know what’s wrong?