I have found a code construct in my code which is marked as error by R#, but VB compiler accepts it.
The variables which are compared are Enums. If i enclose the comparison in braces the error disappears, but it's common in VB to omit the braces.
Another issue is, that a redundant cast warning is marked as error in the marker bar. Further investigation shows that there seems to be a problem with displaying the correct tooltip in the marker bar for large files (the one i'm editing has around 10.000 lines). The redundand cast warning is directly below an error warning
so i think the markers overlap. I've seen it in similar cases that the marker is split in a yellow and a red part, so maybe the behavior is the result of the file size. I also notice this behavior for the combination of TODO items and errors. When a TODO item is only a few lines away from the error (in my case 15 lines) the markers overlaps and sometimes i get the error tooltip and other times the todo tooltip.