Regtest: change the genesis block , can only mine one block

[victorkimba17]

I use bitcoin core 0.15.1 , and change the new genesis block, [by changing the timestamp in createGenesisBlock function, and change the parameters passed to createGenesisBlock, such as CreateGenesisBlock(1231006508, 1170854509, 0x1d00ffff, 1, 50 * COIN) ]

After that , i call bitcoin-ci -regtest generate 1, it can only mine one block. Subsequently, the mining is not successful, as follows:

src/bitcoin-cli -regtest  generate 1
[
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Does anyone experience the same problem?