IO - Budget: During PO creation no error messge while po value exeed budget

HI CO GURUS N EXPERTS,

I want to control the PR Creation by Intern Order based budgeting. For this. I have

1. Created a Budget Profile (T-Code: OKOB): Time Frame Past-1, Future-1, Checked flag Total Value and annual value, Exchange Rate -M, Activation Type - 1, Checked Flag Overall, Budgeting curr. - Controlling area curr.

2.Created an Internal Order Type (E.g. BC01 using T-Code: KOAB), and assigned this budget profile to this order. Other settings are: Order Category - Internal Order (Controlling), Settlement profile- 20 (Overhead cost), Planning Profile & Budget Profile - Both kept as Budget profile (Created by me), Collective Order without goods movement, Residence Time1 - 3 Months, CO Partner update: Active, Checked the flag: Commitment management, Status Profile: Internal Orders.

3. After that defined the tolerance Limit for controlling area as: Tr Group 01 Activity: 1 usage 90% and Tr Grp 01 Activity 3 Usage 98.

4. Created an Internal Order (T-Code: KO01): By selecting Oeder Type Created by Me (e.g. BC01), Enter Company Code, Plant, Object Class as Overhead, under Control Data tab: System Status - REL AVAC BUDG, Commitment update flag is appearing checked.

5. After that in T-Code: KO22, I have assigned budget amount.

6. in KO23 when I press Ctrl+F10 is shows: Availability control is Active, Availability control for: Overall, Availability control in Controlling area currency

Now, when I created the Purchase Order (with Account Assignment Type F), enter the Internal order no. and save it (where budget limit is cross) it does not gives any error message.

Why, Where I have did the mistake. please suggest.

with thanks.

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