How to include not firmed receipt elements (PRs) in the LTP

Hi Experts,

I have ran the LTP MRP using a particular planning scenario, but the results doesn't show any Purchase requisitions, Planned Orders, etc in the long-term window. It shows only firm receipt elements like Purchase Orders, Production Orders only. Any reasons behind this? How to include not firmed receipt elements in the LTP long-term window?

Thanks

Raj