Dates are not updates in PRTs

Question

Scenario is like this
i want to use PRTs AMMETER to check  the Ampare and Voltage of MCC  Panel
i make two orders, in both order the start and finish date is same that is 12.09.2011and time consumed for finish the work is 40 mints
problem:
1> When i am checking the availability the system says all PRTs checked r available,
i am n't understand how it possible at a same time for both the How PRTs Equipment available 
2> After releasing odrer in both order the
Early Start Date = 12.09.2011   Early Start Time = 09:30:00
Early finish Date = 16.09.2011  Early Finish Time = 18:30:00
How i correct this dates + time , and availability

Answer 1

I guess, you have assigned Equipment PRT. For equipment PRT, by default availability check will not work. Availability check is for Material PRT.
This is from SAP Help: (In IMG, Availability check for Material, PRT)
In this section you make the settings that are important for the material availability check and the production resources and tools availability check for components in the maintenance- or service order.
You need a checking group and a checking rule to execute this availability check.
You must assign the checking group to the individual materials by means of material master record maintenance. You define the checking rule for each application. You define the scope of check with the checking group and checking rule.
Note: For Equipment PRT, you can control the business transaction by using User status.