From experience in past MMOs, this sort of things happens.
This thread is a little old, so sorry for posting here again, but I'd really hate for a new RPer to quit a unique and fun hobby because of a bad experience like this. As others have said, sometimes there's a random DC, sometimes it's a deeper reason. Even if this person looks like they have a pattern, it might not be malicious; they could have a bad internet connection or limited access to the internet. And if it turns out they don't want to RP with you, that's an unfortunate fact that you would have to accept. Like in life, not everyone gets along; the same goes for RP communities. Even if two people might not have characters or writing styles that mesh, that's not a personal attack. It happens, and as long as you're trying your best - and much more importantly, having fun - most people won't mind. There's nothing wrong with being new to anything.
I hope you have better luck finding RP partners in the future!