Why is this not docking?

[randomkspplayerr]

 I have been trying for so long to dock but it just wont let me! I have tried multiple different ways and tips but I can't seem to dock! Please help me, what am i doing wrong?

 

Image link:

(The engine trails are because of the screenshot, they aren't on)

https://drive.google.com/file/d/1pAlkLRmhVHlVd6WCqYT17YOGUh1wXktp/view?usp=sharing 

[Vanamonde]

I can't see the picture very well but the most common reasons are 1) one or both of the docking rings is mounted backwards, 2) they're not the same size, and 3) try turning SAS off and see if the rings' magnetism aligns the rings. 

Also, welcome to the forum.  

[Martian Emigrant]

Hi @randomkspplayerr what he said.

 

Looking at your screenshot I can't tell if there is a docking port on the command vessel.

Also I find the 3.1 m distance suspicious. Is one or both docking ports clipped inside another part?

If a part is too close it can interfere with the docking ports touching each other.

Some parts don't have an exact match between the graphics and the actual place where they end.

 

 

 

ME