Ajeh:
If you go to the Modules ... Shipping ... and click on Per Unit perweightunit ... can you copy the information in the right panel here?
Also, what do you have in the Configuration ... Shipping/Packaging ... settings?
Per Unit
Enable Per Weight Unit Shipping
True
Shipping Cost per Unit
*weight
Handling Fee
0
Handling Per Order or Per Box
Order
Tax Class
--none--
Tax Basis
Shipping
Shipping Zone
--none--
Sort Order
0
Country of Origin United Kingdom
Postal Code BD16 1WF
Enter the Maximum Package Weight you will ship 5000
Package Tare Small to Medium - added percentage:weight 0:0
Larger packages - added packaging percentage:weight 0:0
Display Number of Boxes and Weight Status 0
Order Free Shipping 0 Weight Status 0
Shipping Estimator Display Settings for Shopping Cart 0
Display Order Comments on Admin Invoice 1
Display Order Comments on Admin Packing Slip 1