Assigning Serial No. to PR in SAP MM

We want to trace the material ( T-8000 : Semi-Finished )  activities with serial numbers. I created a new serial no. profile by the following activities…

1. Business Function, LOG_MM_SERNO is activated through SFW5 transaction.
2. Created a new profile within OIS2 transaction ( Z003 : PRSL & POSL ) with SerUsage : 01 & EqR : 02.
3. IMG: Materials ManagementàPurchasing-->Purchase Requisition-->Define Document types with SerUsage : 03 & EqR : 02.
4. IMG: Materials ManagementàPurchasing-->Purchase Order-->Define Document types with SerUsage : 03 & EqR : 02.
5. Assigned the profile “Z003” to “General Plant Data / Storage 2” view of Material Master.

After doing the above settings, I tried to create a Purchase Requisition in ME51N.

In Material Data tab, I selected Assign Serial Number . Clicking on the Icon brings up the Maintain Serial Numbers window where I cannot find  “ Create Serial Number Automatically ” option.

When I tried to enter the serial no. “2” manually, the following Error Message is Displayed “ No New serial Number can be entered for material T-8000 (2) - Message no. IO214”.

Pls Guide me.

Thanks in advance,

Dinesh Kumar V.