Need help with HDMI mirroring to monitor

Hey all, this is a "what am I doing wrong" post, let me know if this has already been answered!

I have a personal project where I want my rooted Verizon Galaxy Nexus to mirror on a 7" computer monitor that is HDMI capable. I have the MHL->HDMI adapter and have connected everything (HDMI cable, power to MHL->HDMI adapter), but it does not mirror to the monitor. It seems to be caught in a loop where it attempts to sync, gives up after a few seconds, then tries again. I don't get a picture. ONCE, for about half a second, I got a picture while playing a video on my phone, but I have not been able to duplicate that.

I tested my desktop with the 7" monitor, and it worked fine.

I tested my phone with my Samsung TV HDMI, and it mirrored fine.

I tested my phone with my non-Samsung HDMI computer monitor, and it did not work at all.

So, does this sound familiar to anyone? Suggestions? Questions? Thanks in advance!

Addendum: I may have rooted the device, but it's still running what Verizon put on it, and it's getting updates. It's on Android 4.1.1 right now.

I just read in another forum that the MHL to HDMI adapter may be at fault. I got a non-Samsung one. Since getting a Samsung one is not terribly expensive, I'm going to try that, and update here if I get different results.

i bought a samsung one off of amazon for 12 bucks i works great for monitors and TV's