Preqs not transfer to ECC

Hi Experts,

The Purchase requisitions(SNP Heuristic) are not transferring to ECC system from APO for the one location product combination.And it is not at all updating in MD04.

We have checked all the necessary steps,

1> Queue manager - checked (No q 's)

2> Publication type - Checked (APO)

3> Distribution definition -Maintained in APO

4> CCR checked

5> number ranges -Checked in both ECC & APO.

The above steps checked and all maintained but however i couldn't find the root cause..

Please help us....on this.

Awaiting yours(Experts) reply....this is an urgent.

Thanks

GP