Hi
Can you check if the plant is added in the attributes of the user creating the shopping cart.
Implementation Guide for R/3 Customizing (IMG) -> Enterprise Structure -> Definition -> Logistics - General> Assign plant to company code
Implementation Guide for R/3 Customizing (IMG) -> Enterprise Structure -> Assignment -> Materials Management -> Assign purchasing organization to company code
Implementation Guide for R/3 Customizing (IMG) -> Enterprise Structure -> Assignment > Materials Management-> Assign purchasing organization to plant
cross check all the above settings. May be the links below will help you.
storage location not defined for delivery item | SCN
https://scn.sap.com/thread/1887010
Hope it helps.
Regards
Bash