Very likely you need to tell your PHP JSON RPC client to connect to the right port.
If you start bitcoind without -regtest
(= main net), it opens up the RPC server on port 8332
.
If you use -regtest
, the port will be 18332
.
I can't see what kind of PHP JSON RPC client youryou are using, but there must be a way to tell it should use port 18332.