Change IMEI Huawei Um840 Furious Gold

Good afternoon, anyone can help me? I have tried to repair the imei of huawei um840 using my furious goal box, and I get the following error:



Model name: UM840

Firmware: M7x25V100R001C00B251

IMEI: 353834041528436



2014-07-02 19:23:33.171 Repairing IMEI...

Connecting to server... OK

Sending data to server... OK

Reading data from server... OK

Sending data to server... OK

Reading data from server... OK

Unlocking NV items... failed!

Sending data to server... OK

Reading data from server... OK

Disconnecting from server... OK

Failed unlock NV items

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