The first thing I would check is make sure you have the splitter hooked up correctly. It is very common for people to actually have the input from antenna going into the out on the splitter. I just bought my RV and it was hooked up that way. I am a cable guy and I see it all the time!
Next check fitting to make sure there is no braiding touching the center conductor. This will cause massive signal loss.
You definitely want to buy a long cable and barrel directly to line coming from the antenna. Try both tvs separately. If they work fine you will know it is splitter, wall plate, or cable line that is the problem.
Also make sure it is a 2-way splitter with 3.5db loss on each leg.