MRP didn't change planned order to Purchase requisition

Hello

I have a problem with my MRP on an item.

my MRP runs on sunday (in my example : the 2nd of june 13 > 02/06/13)

MRP profile : 0010

scheduling

GR processing time = 5 days

SchedMargin key = 002 (6 days)

delivery lead time = 154 days

planning calendar = 520

Here is the periods of my calendar around my requirements :

From date           Period to           period

1. 28.10.2013 10.11.2013          44/2013
2. 11.11.2013  24.11.2013          46/2013
3. 25.11.2013 01.12.2013          48.2013

I have a requirement which is fixes on the 11.11.2013.

I supposed system choose 11.11.2013 with calendar.

then, delivery date should be 05.11.2013 (-5days for GR processing time / without sundays)

then, 04.06.2013 (-154 days for delivery lead time)

My opning zone is between the 02.06.2013 and 08.06.2013 (schedmargin key).

According to me, MRP should create purchase requisition and not planned order !!!?  (attached file in french, sorry)

the problem is that during the week, this planned order get frozen because of the changing period.

Why did it create planned order ?

Is there something i didn't understand ?

What can i check to unlock my PR ?

I have got some items with no probs. same scheduling but with PR creation.

Thanks

Martin