Thanks for the reactions. I now discovered what the problem was I was facing. The song I am working with has lyrics and I expected that when deleting a certain number of bars that the lyrics in thos bars were deleted as well. I think that's logical. However it is not true. One has to delete in 2 steps. First the lyrics and then The actual number of bars.
I have a song which I want to separate in a number of parts. So I copied the song 5 times and named them part1, part2 etc. So from part 1 I want to remove the first x instrumental bars, then keep the bars with lyrics till a certain point and then delete the remainig bars.
With part 2 I want to keep an other lyrics part and delete what is not needed.
Also with parts3, 4 and 5 I would like to do the same.