Most likely you have made an error somewhere in editing the schematic. Left a volprobe hanging in space no longer connected to a net is one possibility..? Look at the bottom of the `Simulation Results...` window for an error message. For more help, post the contents of that window back here or better, make a copy of your circuit public - and post the url to it back here - or share it using Access Contol: https://easyeda.com/Doc/Tutorial/share.htm#Sharing

I think the problem was that I renamed the probes. Because I had the probes on the two inputs and the output of an op amp I renamed the probes to "in +", "in -" and "out". When I deleted those renamed probes and replaced them with new probes, this time without changing the names, it worked. Then I changed the name of one of the probes and it didn't work (again). I don't think you should change the probe names, even though the app lets you.

You can change the names of volProbes and nets as you like but there are some rules and caveats to observe when doing so. The immediate problem you have encountered is that when naming nets and volProbes, the following characters only are allowed: letters `a` through to `z`, numbers `0` through to `9` and underscore `_` Note that: i) letters are case insensitive; ii) spaces are not allowed. For more on net naming and probing signals in EasyEDA, see the EasyEDA Simulation eBook at: https://docs.google.com/document/u/1/d/1OWZVVFRAe_2NW3WratpkA_SGuHa5AcRow5ZRfvcoVTU/pub In particular: **Probing signals:** https://docs.google.com/document/u/1/d/1OWZVVFRAe_2NW3WratpkA_SGuHa5AcRow5ZRfvcoVTU/pub#h.z337ya **Advanced probing and simulation control:** https://docs.google.com/document/u/1/d/1OWZVVFRAe_2NW3WratpkA_SGuHa5AcRow5ZRfvcoVTU/pub#h.4i7ojhp (The Google links above are to the original copy of the Simulation eBook which you can also find at: https://easyeda.com/Doc/Simulation-eBook/ but the table of contents in the EasyEDA copy is broken and misses out some sections. We are working to fix it but in the meanwhile the copy published to the web from Google Drive works just as well.)

Thanks very much for the information. It would be nice to be warned or to receive an error when changing the name to something that is not permitted. I had a similar problem when I assigned a value of .1uf to a capacitor instead of .1u. To confirm my suspicion that invalid values weren't being checked, I changed the value to .1z. Again, no error or warning.

Not sure why you had a problem with .1uf because that is valid. The allowable suffices for components are given in the EasyEDA Simulation eBook. Can't remember which section but it's near the front. You'll also find that info in the original ngspice manual. I agree though that better error reporting is needed.

The information about suffices is here: **About naming conventions:** https://docs.google.com/document/u/1/d/1OWZVVFRAe_2NW3WratpkA_SGuHa5AcRow5ZRfvcoVTU/pub#h.3dy6vkm The ngspice manual is here: http://ngspice.sourceforge.net/docs/ngspice-manual.pdf (The Google link above are to the original copy of the Simulation eBook which you can also find at: https://easyeda.com/Doc/Simulation-eBook/ but the table of contents in the EasyEDA copy is broken and misses out some sections. We are working to fix it but in the meanwhile the copy published to the web from Google Drive works just as well.) Reply