Unable to add nodes to automation...

Today I was adding some automation nodes to several track volume envelopes and Sonar was doing (or not doing) the strangest thing:  If I added two nodes, say to create a fade out so the first node was higher than the second, I could NOT add a node in between them.  In fact if the two nodes were of demonstrably different heights  I couldn't add a node either.  I could add as many nodes as I wanted as long as my envelope was relatively "flat".  It got to where it was tickin me off pretty good and I don't know, but I may have hurt Sonar's feelins with some of the plum awful things I said to it.