Thank you very for the help.
It helped me to solve my problem.

Best regards.

>>Hi,
>>
>>I have a table:
>> Rate_Memb N 12 2
>> Eff_date D
>>
>>Index Eff_date on Eff_date is a candidate index.
>>Buffering mode is optimistic table buffering.
>>
>>Users should enter Rate_memb and Eff_date manually.
>>In the textbox Valid event I validate This.Value:
>>
>>Local lRet
>>
>>lRet = !Seek(This.Value,"ratememb","eff_date")
>>if !lRet
>> =MessageBox("Duplicate effective date.",16,"Members rate")
>>endif
>>
>>Return lRet
>>
>>But On Seek() I got error on uniqness violation.
>>
>>What are solutions of the problem?
>>
>>Sincerely.
>
>Both John and Bob's suggestions are valid, I just wanted to throw in that if you are using VFP 6.0, this is an excellent place to use INDEXSEEK instead of seek. That way you can check for duplicate values without moving the reocrd pointer.