I recently built pdnext from source on my Linux system (Mint Debian Edition), and i've had a few problems.
First it wouldn't connect to my MIDI controller (Novation Launchkey Mini MK3), due to it being mislabeled as an audio device.
This was solved by running aconnect and connecting the ports via the terminal. However, pd still won't receive any midi messages from my controller. I ran

amidi -d -p hw:1

on the terminal (hw:1 being my controllers MIDI Port) to make sure data was being received by my computer, and had no problem. So it has to be something happening in pd where the information gets lost.
Would really appreciate some help with this.

@Pepe_mv98 Does your device now appear in the Pd top menu...... "Media", "Midi Settings..." ?
David.

@Pepe_mv98 You need to connect the device to pd first, run amidi -l to get a list of available input and output ports and then use aconnect to connect them. You can also use aconnect -o and aconnect -i to list output and input ports as well and is helpful when you have a good number of devices to sort through. The man pages for these two programs should answer any other questions you have. And there are various ways to automate and simplify these connections but for simple setups like a single connection I never found the need beyond writing a very simple script which I lost and never bothered to rewrite.

Nope. When I enter MIDI Settings there is only this:

@oid Something odd: when i run aconnect -i or aconnect -o it lists PD's ports backwards ("Pure Data Midi-Out 1" as input, "Pure Data Midi-In" as output). Is it supposed to be like this?

Issue was solved. Turns out all this time i was connecting my controller's input port to PD instead of it's output port. Thanks for the help