Hey! This is my first project in EasyEDA. (also sorry for my bad english) I am making this as part of a Project for university. In this project I want to build a selfmade "Ladder Filter" with templates from Bob Moog. This is basically an array of transistors (hence the name "ladder") which functions as a 24dB/Octave Low Pass Filter with an integrated Feedback loop for self oscillation/ saturation. ![Ladder Filter Layout.png](//image.easyeda.com/pullimage/NNMLC3imdTi7gxs8VQwBD1AROn68sHyLYMf5b55x.png) Before building my circuit I tried to simulate it and built the schematics as you can see in the picture above. Every time I try to start the simulation, it shows an error with an "unknown subcurcuit called in". I`m quite desperate right now.. :D If someone could tell me what my mistakes are in this simulation, i would be very happy and greatful.