I have RequiredFieldvalidator problems on the server but not on my machine

Hi,

On the production server I have this problem:

I have required field validator on the page associated to mytextbox. The first time I refresh the page every thing works fine, meaning: if I enter no text in mytextbox and I press the submit button, I see the error message associated to the requiredvalidator displayed close to my text box "required field".

Then, I enter a text in the textbox and press submit, naturally, The error message "Required field" disapears.

The problem: when I delete my text and press submit again, no "required field" error message is displayed.

It only works the first time my page is refreshed but never again.

All this happens only in my production server but never in my development machine.

Any explanation please?

Thank you.