Bukkit

What steps will reproduce the problem?
1.create shop with sign
2. shift - rt click on sign
3. choose 'buy' option
4. Select item from inventory
5. Prompted to 'Insert a price'
6. typing numbers does nothing, just changes what inventory item in my hand is selected

What is the expected output? What do you see instead?
I expected to be able to set the price for the item

What version of the product are you using?
2.3

Please provide any additional information below.
Use Lockette but have enable-quick-protect: false

Using MCPC-plus-1.6.4-R2.0-forge942-B127 as server jar

It appears as though this is an obsolete method of setting up the shop (although there are a couple of videos using this). You have to follow the instructions on the wiki