There is no row at position -1

[torrud]

That error means that you try to get access to a row by index -1, but rows are always zero-based. Through this rows with negativ index do not exist.

In most cases -1 means that there is no entry in a collection you are looking for, for instance the method IndexOf() returns -1 if the object is not in the collection.

But I am not a fortune teller, so I can not say clearly what the error in your code is without having a look at it.

[yusufozkay]

"There is no row at position -1" what is the reason of this exception? I couldn't understand the reason of this, because it occurs random I think. I didn't come across this exception while debugging the program for hours.

[torrud]

Nice feature of the board to show the answer above the question.

[Jason Isom]

But I am not a fortune teller[snip]

I beg to differ! Answering the question before the question is asked is definitely divine. :P