unable to use resolution other than super resolution

[punkysuen]

I have an arcade cabinet Sega New Net City with a try-sync monitor, and I hook it with PC to run emulators.
I am using Windows 7, and my video card is AMD R9 290 4GB, without VGA and DVI-I ports, so I use HDMI-to-VGA adapter.
I have installed crt_emudriver and followed the guide to install modes by super resolutions.
Everything goes fine when I play GroovyMAME, super resolutions are great.
By GroovyMAME, every 15KHz and 25KHz games show properly.

However, when I play Nebula's Model 2 emulator, the image is abnormal if I choose super resolution 2560x384.
I cannot find "Image Stretch" function on this emulator.
Therefore, I tried to add 496x384 by editing the txt of super resolution.
The result is "No Signal".

After trying different settings, I found that native 640x480p works normally, all other custom resolutions (like 320x240, 496x384) fail.
What I can use are super resolutions only.

Anything I can do to use custom resolutions?

Thank you very much!

[Calamity]

After trying different settings, I found that native 640x480p works normally, all other custom resolutions (like 320x240, 496x384) fail.
What I can use are super resolutions only.

Are you using CRT Emudriver beta 14?