[Rwp] My item refuse to be pasted were the cursor is placed!

[ROBIN Alexis]

Hello all,

     I met a strange problem when editing item with Reaper.
I have a drums beat, each item representing a 4/4 part. If I want add a 
new 4/4 between the second and the third item, my past will be placed at 
the beat 2 and not at the beat 1, even if my cursor is on the beat 1.
I think it's because the precedent item go over the edge on the beat 1. 
But when I past my item in last position, the result isn't forwarded at 
the beat 2.
Do you know what is the issue?

Thank you so much,