This error is caused by Apple Store purchase problems． Please try the following methods to solve this problem．
Visit the Apple Support Center at: http:/www．apple．com/support
Step 1: Enter the Apple Support Center on your computer and select the iTunes icon in the lower-right corner．
Step 2: Select ”Get Support” in the lower-left corner．
Step 3: Select the ”iTunes Store Support” link in the center of the window
Step 4: Click ”Purchases, Billing and Redemption”
Step 5: Select ”Unable to purchase from the iTunes Store” in the pop-up list
Step 6: Choose the appropriate contact information for support
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Game Guide for Last Empire – War Z