Input SDI Atem television studio HD 1080p/50

Goodmorning everyone,
I need some advice, as I can't figure out where I'm wrong in the links.
I need to connect cameras to the Atem television studio HD, but they only support 1080p50 format.
The problem does not exist as the director supports this format. The problem arises when I convert the links to SDI.
Let me explain: considering that I have to put the cameras 100 meters away, I wanted to use the SDI inputs, so I connected the camera with an hmdi / sdi converter and then connected the SDI cable to inputs 5/8 of the HD television studio .
Here is the problem, the camera is no longer visible, if I insert a reverse converter it works in the hdmi 1/4 inputs, how come? SDI inputs should accept 1080p50 format .....
Thank you in advance and look forward to your kind advice.
THANKS

Can't anyone help me?

What kind of HDMI/SDI converters do you use?

There are a lot of cheap ones that don't output a real 1080p50 SDI signal according to SMPTE specs. Others have very cheap SDI drivers that can't drive a 100m cable.

Cheers

Robert