How to Maintain Stock

Sir, please tell me, how to maintain stock?  My Co.  is selling spare parts for bike. I have purchased some parts. I entered all the parts entries by creating stock groups & stock items. Further I purchased some items if same item is repeated it shows error duplicate entry.  How to make next purchase entries?

Kusum from India 

Kusum, actually, you did not pass the voucher entry of purchase. You have  just created  inventory ledgers by creating of stock items. When you went to create inventory info for creating stock items, you can create each item one time. After coming back, you have to go to voucher entries. Select purchase voucher and then pass the voucher entry of purchase. If you have purchased on credit, you need to create the party name ledger by using short cut command Alt + C. Only after this you can pass the voucher entry of purchase. If you did not create the ledger of purchase, please also create it in account info. If you also sell the spare part of bike. Please pass the voucher entry of sales. Only after this, you can check net balance of your inventory.