Hi: I am newbie in EasyEda,so I have the same problem like: [https://easyeda.com/forum/topic/New-to-easyEDA-user-Please-help-cant-solve-this-error-Fatal-Error-Unknown-subcircuit-called-in-xu1-gnd-xu1-2-cu1-3-vcc-xu1-5-xu1-2-xu1-7-vcc-ne555n-ecb0960f91994056aa7d749c7b4f3c14](https://easyeda.com/forum/topic/New-to-easyEDA-user-Please-help-cant-solve-this-error-Fatal-Error-Unknown-subcircuit-called-in-xu1-gnd-xu1-2-cu1-3-vcc-xu1-5-xu1-2-xu1-7-vcc-ne555n-ecb0960f91994056aa7d749c7b4f3c14) so i cannot find any information how could i add one simulation property to for example IC555 in my EasyEDA Schematic file as you could see here: [https://easyeda\.com/editor\#mode=sim\,id=\|159679bb4bae460baca0f562db2247ec\|03eda222e44e40ac91aae4c09fb44163\|e89fc4c974714cd0b522615621da1138](https://easyeda.com/editor#mode=sim,id=%7C159679bb4bae460baca0f562db2247ec%7C03eda222e44e40ac91aae4c09fb44163%7Ce89fc4c974714cd0b522615621da1138) So i searched  via internet and find [some instruction](https://www.youtube.com/watch?v=BEw2kqQkM1M) to work with simulation and based of those i have made one like this which could be done: [https://easyeda\.com/editor\#mode=sim\,id=\|159679bb4bae460baca0f562db2247ec\|03eda222e44e40ac91aae4c09fb44163\|e89fc4c974714cd0b522615621da1138](https://easyeda.com/editor#mode=sim,id=%7C159679bb4bae460baca0f562db2247ec%7C03eda222e44e40ac91aae4c09fb44163%7Ce89fc4c974714cd0b522615621da1138) As [here](https://electronics.stackexchange.com/questions/255643/unknown-subcircuit-in-ltspicexvii) ([“Unknown subcircuit” in LTSpiceXVII)](https://electronics.stackexchange.com/questions/255643/unknown-subcircuit-in-ltspicexvii) said : > LTSpice can't find the sub-circuit for the device how can i change those for simulation, SO could you give me some advice to do it? This Question link in [StackExhcange](https://electronics.stackexchange.com/questions/465516/circuit-sheet-1-fatal-error-unknown-subcircuit-called-in-xu1-gnd-u1-2-u) forum. Thanks.