Has something changed in 1.57 that prevents two installations of Zencart from using the same database? This will be the third time over a six-year period that I've moved a test install to the live database, and I had no problems the first two times. I was using 1.55 both of those times and changed the two configure.php files without any problems. This time, I either get the "Can't open database" error message, or just a blank screen on both the store and the admin sides.

I'm aware that a blank screen generally means some php syntax error but I've looked at these two files until my eyes have crossed and don't see anything wrong. For once I remembered to check the error logs before asking here, and there are no error entries for today. I also actually remembered to set the ftp program to transfer text instead of binary. So there shouldn't be any hidden characters in the files. I was careful not to confuse the store configure file with the admin configure file. I'm out of ideas.

Live installation: https://www.newnaturalsonline.com
Test installation: https://www.zentest.newnaturalsonline.com

Thanks for any suggestions.