The above problem has just appeared when running a script for the first time (on my machine) in DIAdem 2021, having worked perfectly in 2020.
The offending line of code (not the one in the error message but the one at which the problem actually occurs) is:
...but this is only the problem line because of what takes place just prior. Having started with two groups of channels, the code deletes the first group as it is not needed any more. The second group becomes the first group and channels 1 and 6 are to be plotted using the above line.
However, what seems to be happening is at the point of deleting the first group the data file is not updated so that the above line tries to add channels 1 and 6 from the first group. These are now empty and not available, although the group and channels still appear to be listed in the portal.
As I write this I've also discovered that previous channel deletions also fail in the same manner. The two 'Time' channels in the following image should have been removed before any of the above takes place. I've shown the 'Latac' channel in the first group as highlighted but you can see in the boxes below there are no details for that channel.
In short, it seems that using the Remove method is not working properly.
Regards, Simon.