erratic date picker

Hello,

I have two forms with date pickers. They were working fine. Now in one of the forms the date picker does not work any more. If I put it in the other form (copy and paste) it works. Both forms use the same picker, which is equally imported through the @extends('layouts.app') Am I dreaming? Do you have a clue?

<div  class="form-group{{ $errors->has('projectstart') ? ' has-error' : '' }}">
                        <label for="projectstart" class="col-md-4 control-label col-md-offset-4">Projekt Start Date</label>
                              <div class="col-md-4">


                                
                                    <input type="text" id="projectstart" class="form-control datepicker" name="projectstart" value="{{ old('projectstart') }}" required autofocus />
                                 

                                    @if ($errors->has('projectstart'))
                                    <span class="help-block">
                                        <strong>{{ $errors->first('projectstart') }}</strong>
                                    </span>
                                    @endif
                                


                            </div>
                        </div>