Connecting tacktick triducer to old tridata

[tonymacina]

Hello everyone!
I have a brand new tacktick triducer and I was wondering if it is possible to connect it successfully to my old ST50 tridata.
I tried to match wires color by color, and while speed works perfectly, depth does't seem to work even if I put the transducer in the water.
I also tried to connect the screen to the depth plug instead of the speed plug on the back of the instrument, but while speed works anyways, depth doesn't.
I have downloaded the electric diagram of the tacktick triducer from airmar website, and it seems slightly different from the st60 triducers diagrams for what regards the screen wire (st60 triducer should be fully compatible with st50).
Any help?
Thanks
Tony