File input doesnt show up in $_POST [duplicate]

I have this input form field:

              <div class="inputContainer">
                <img src="images/3_randomfilm.jpeg" alt="image" width="100">
                <label for="radioEdit1" class="labelForm radioLabel">Afbeelding
                        <input type="radio" name="radio" value="radioAfbeelding" id="radioEdit1" onclick="showEditInput('file')" checked />
                        <span class="checkmark"></span>
                </label>
                <label for="radioEdit2" class="labelForm radioLabel">Video
                    <input type="radio" name="radio" value="radioYoutube" id="radioEdit2" onclick="showEditInput('url')"/>
                    <span class="checkmark"></span>
                </label>
                        <input type="file" id="fileEditInput" name="fileEditInput" class="input hidden" accept="image/png, image/jpg, image/gif, image/jpeg">
                        <input type="url" id="urlEditInput" name="youtube_url" class="input hidden" value="">
              </div>

When I try to post this, everything posts except the fileEditInput. I just dont get it… Why does this not post?

 <input type="file" id="fileEditInput" name="fileEditInput" class="input hidden" accept="image/png, image/jpg, image/gif, image/jpeg">

This is how I post it in PHP if you want to know:

$_POST['fileEditInput']

I tried giving it another name, but I just dont know how this can be wrong. Maybe I mistyped something but right now I cant just see it…

I hope you all can help me…