Approval for exceeding credit limit for particular bussiness partners

Hi Experts,

I am trying one approval for the Business partners for credit limit exceed.I have tried through standard Approval process by using the terms deviation from credit value as described but what should be done if i need to set it for particular business partners.

Also, in this standard query which i have tried i have defined the terms as :-

Deviation from credit limit greater than or equal to 50,000 . I have set this terms for A/R Invoice. Now when i have made the invoice for rs.5000 then also it is asking for Approval.Since the Value is defined so system should not ask for approval.

Regards-

Mona.