Error 1077 Property Node Active Plot

[murchak]

I have this strange problem: My VI uses the File Dialog to open a number of files for plotting. If I open say 3 files, everything works, next time I run my VI and open say 5 files (>3), 

I get "Error 1077 occurred at Property Node (arg 1) in xxxx.vi. Possible reasons(s): LabVIEW: Invalid property value. Property Name: Active Plot."

When I run again the VI, all 5 files open and work fine. Again, everytime I open a lower number of files, say 2, 3, 4, etc. and run the VI and open a larger number of files, I get

this error. Any ideas? below is a picture of the VI block diagram (part of it anyway)

[smercurio_fc]

If the plots haven't been drawn yet, then you will get an error trying to access a non-existent plot. That's why you get the error when you first open 3 files and then 5 files. Those 2 additional plots haven't been added to the graph yet.  One thing you can do is to set the Legend:Plot Minimum based on the number of files you selected.

Code comment: You seem to be somewhat waffling in your code as to whether to use auto-indexing or to wire N and use Index Array inside. With two of the for-loops there you can simply auto-index. In one of the for-loops you have both N and are auto-indexing. This is a no-no. Do one or the other, not both. What exactly are you doing with all those loops?