Storage type search - 2nd storage type

Hi,

In the storage type search sequence there are multiple storage types which can be entered in fields 1st st type, 2nd st type, 3rd st type etc.

My question is under what circumstance does the system select 2nd st type.

I have a scenario where the 1st st type is active, all the configs are in place, there are empty st bins availble in 1st st type, but system bypases this and selects 2nd st type. I am observing this only for a particular material.

What could be the reason?

Note - All the config settings are in place, and material master also updated with the correct st type indicator.

Regards

MS