Why are the Mekanism teleporters work only on one way?

[Engrayight]

I wanted to go to a new place far from my base to mine with Digital Miner. I used nether portals for this, but it was too slow and laggy, so I decided to make Teleporters with Wind Turbines. The A portal is on my base, the B portal is on the 'mining place'. I build A first then I used the old portals for the last time to get to the 'mining place'. After I built the B portal and I tried it. It worked, I got teleported to the A portal. But after a minute I had to realize that I can't go back. I used /tp and tried it again: from B to A worked, from A to B didn't. What is the problem? If you can please don't send answers with 'Try'.

Sorry if I made mistakes, but I'm not English and the past tense is my weak point. But I hope I was understandable.

 

[Omegatron]

They should be bi-directional. Is the B end chunkloaded? If it is maybe there are power issues.

 

[Engrayight]

Thank you! I tried it and now it's working. The A portal is maybe in the spawn chunks and that's why it's worked.