Testnet spending keys should start with 'TK'.

src/chainparams.cpp

@@ -187,7 +187,7 @@ public:
         base58Prefixes[EXT_PUBLIC_KEY] = boost::assign::list_of(0x04)(0x35)(0x87)(0xCF).convert_to_container<std::vector<unsigned char> >();
         base58Prefixes[EXT_SECRET_KEY] = boost::assign::list_of(0x04)(0x35)(0x83)(0x94).convert_to_container<std::vector<unsigned char> >();
         base58Prefixes[ZCPAYMENT_ADDRRESS] = {20,81};
-        base58Prefixes[ZCSPENDING_KEY] = {171,55};
+        base58Prefixes[ZCSPENDING_KEY] = {177,235};
 
         vFixedSeeds = std::vector<SeedSpec6>(pnSeed6_test, pnSeed6_test + ARRAYLEN(pnSeed6_test));