FTB Tesseract spits items back

First the standard fromt he checklist. Yes they are the same frequency, yes they are chunk loaded.

I have a quarry with a BC transport pipe (stone) connected to a tesseract that is set to send items only. I have another tesseract with the same frequency set to receive items only. However the sending tesseract does not send anything, the blocks fall out of the pipe right close to the tesseract.

I even tried the dummed down version with just pulling stuff out of a box which works fine but the same problem, as soon as the items go into the tesseract they come right out again and are not being transported.

I also tried just leaving an open pipe as the end... it looks the same. To me that indicates that the tesseract never actually takes the item in. Why?