Ted not knowing the make, model and year of your RV, and not knowing the model of your WFCO Converter, we are at a disadvantage. Here is a clicky that will tell you everything I think you need to find your problem.
CLICKYI am suggesting that you should look at the document I have provided rather than us trying to tell you what to do. Assuming from what little info you gave us, the 12vdc from the converter is connected to your fuse panel and therefore, to the battery. So if you check at the converter you may be getting a reading from the battery and not from the converter at all. But if that were true, the all the fuses would have to have been blown not to have DC power.
Read the trouble shooting part of the manual for your converter and if then you have questions, feel free to ask questions but please let us know all the info I mentioned in the first sentence.
I am truly trying to help you so don't be offended, just help us help you.