Hi,
Still not working but I have made it work running firstly the AMCap ST4 Test. After running this test I am able to control the ST4 using MaximDL and both Guider relay and ST4 ASCOM driver.
If I reboot and try MAXIMDL first the ASI ST4 port does not work. It seems the AMcap ST4 accomplishes some camera ST4 initialization that makes further ASCOM drivers work.
Hope this information can help you solve the problem.
Andre Mouitnho