Are you playing on PC or Mac? Did you change the executable file to include "patchme"?
https://www.project1999.com/forums/s...d.php?t=273874
https://www.project1999.com/forums/s...d.php?t=157069
https://www.project1999.com/forums/s...d.php?t=314306
These were 3 different threads i found when searching for DSETUP.DLL P99. All of them seem to point towards the same problem: Anti-Virus software. It seems anti-virus software has a nasty habit of doing a quarantine on the DSETUP.DLL file that's proprietary from P99 (should be part of the patch you use to copy files over to the main Titanium client). Try adding an "exemption" for this file through your anti-virus software (if in fact you are using one). The threads give a better explanation of it than I do, but every single one I found all pointed as this being the common fix for this problem (found some threads dating all the back to 2012 with the same issue).