cant unlock sony c1905


pls team how can i unlock this sony c1905

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^ ROMaster Composite ADB Interface
Version: Linux version 3.4.0 (user@su-buildpc-02) (gcc version 4.7 (GCC) ) #1 SMP PREEMPT Fri May 9 12:55:32 CST 2014
Phone model: Sony C1905
Android 4.3; Firmware: 15.4.A.1.9; Date: Fri May 9 12:51:17 CST 2014
Version: 15.4.A.1.9
Baseband Processor: QCT MSM8627 MTP
Software IMEI: 35xxxxxxxxxxxx
Please send
C:\Users\xxxx\Documents\SigmaKey\temporary backup0961059349398_Sony_C1905_15_4_A_1_9_Fri May 9 125117 CST 2014 (4).skb
file to support@sigmakey.com
Data checksum error