A: 

Maybe you could use a CustomValidator and a ServerSideValidationExtender with Ajax:

Tim Schmelter  2010-05-11 08:57:11
sorry , but i don't know how your answer realted to my question .. could you explain ?my problem : is my checking every key up is the best solution or is there any other ?
Space Cracker  2010-05-11 09:05:04

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