Hi,
- defining packing material in VHAR and also check
2. check whether the packing material and packing material is assigned to the material(mm01) in sales general plant tab.
3.Aslo tell me whether your are using serial number for the material .incase if you are using serial
number you have use same serial number you use number for returns also.
sorry boss, didn't get your point clearly you means, number range for both FERT and LEIH?
4.while packing you have select both material and packing material together and click for packing.
Edit pack
Yes, after enter in to Delivery Order "VL01N', select the specific line item, go to Edit > Pack
Then enter the Packing material press enter and select the line item and packing material line, and go to menu Edit > Pack > Pack. in result the line item packed and remove from Material to be packing area, go back to main screen of Delivery (where new line item created with item category "TAL", with number 90002. enter Plant and Sloc for LEIH line item but system shows Info and Error message. Even if do the picking for FERT and LEIH. after ward when pressing PGI button for Posting system shown.
Pls guide further 
regards
Shoaib