About diplomacy, please help me.

[fatiaoqishi]

I reached level 20 and I had just found out I could use the diplomacy on the map to "parley". I found out I only have one ally which is Poland, and when I try to parley with Russ, it says get lost, and when I try to parley with Poland, it says I'm not the Landmeister of the Teutonic Order..
What should I do? I really want to get some of the Russ mounted archers. Does it mean I will never be able to ally with Russ, Prussia, or other countries?
Thank you in advance!