Material marked for deletion

Hello,

A particular material is marked for deletion, but then when i put the same in sales order it does allow me to save the sales order. it give a warning message that :material is marked for deletion/; message number is v1401 i want to make this warning message as error message , kindly some on eplease guide me how to go about it.

Requirement; Material marked for deletion when entered in sales order should not allow to save the so

Regards

Sunaina