Sending data from client-side script

[Eric]

Hi,

I need to use a VBscript to do client-side data treatment (call of a DLL)
and then I want to send the data to server via a INPUT (with a Form submit).
This works very well with classic HTML, but not when I am using ASP.NET. I
do not succeed in putting data in the INPUT element. For example ,
document.MyForm.MyInput.Value = "abcdefgh"
or
document.MyForm.MyTextBox.Text = "abcdefgh"
failed.

How can I do this ?
Thanks.

Eric