Enter a material from storage bin &

What causes this issue?

On the initial screen you entered 'storage bins" and materials from
different storage bins.

System Response

The system only acceps materials from the same storage bin.

How to fix this error?

The storage bin is defined as the bin for the first material. In the
other items only enter materials in the same storage bin. If you
require materials to be entered from a different storage bin, create
another document for these materials.

Error message extract from SAP system. Copyright SAP SE.