Sales order does not appear in MD04

Hello,

One of my sales order is not appearing in MD04. I found out that in the sales order, the requirment type is missing.Is this could be te resaon for sales order not to appear in MD04.

2nd question) why requiremment type is not there in sales order. In my case, there is no entry in the item cat and mrp type table but in the strategy group in material master, the requirment type exists. so why the system is not showing requirment type in sales order by picking it up from the strategy group. in the item cat +mrp type table, the source is kept as "0", which means the system should pick the requirment type from strategy group . so why it is not picking if it is defined in straetegy group ?/

Question 3) or is it that the sales orders appear in MD04 only after MRP run but then why other sales orders are apearing before MRP run.

regards

sachin