Hi Geoffrey,
Its very difficult to explain.. but now I comment line by line my code.. and I found source of problem.
I have a fieldset
* <ext:FieldSet
* ID="FieldSet3"
* runat="server"
* AutoHeight="true"
* CheckboxToggle="true"
* Collapsed="true"
* Title="Filter by Date" >
<AjaxEvents>
* <Collapse OnEvent="OnFieldSetExpand" Buffer="250">
* <ExtraParams>
* <ext:Parameter Name="fieldsetname" Value="fieldset1" Mode="Value" />
* <ext:Parameter Name="expanded" Value="false" Mode="Value" />
* </ExtraParams>
* </Collapse>
* <Expand OnEvent="OnFieldSetExpand" Buffer="250">
* <ExtraParams>
* <ext:Parameter Name="fieldsetname" Value="fieldset1" Mode="Value" />
* <ext:Parameter Name="expanded" Value="true" Mode="Value" />
* </ExtraParams> *
* </Expand>
* </AjaxEvents>
*
and User control which contains UploadFileFiled...
So.. If I remove from code UploadFileField - all works super... or If I remove from code <AjaxEvents> for Collapse/Expand - also all works super.
I am not realy understand why it so.. but.. now OnCollapse/OnExpand - its artifact code.. was created in time when I have no idea which property change value when checkbox was checked and area expanded. - Now I found the proeprty is "Collapsed" - so.. I hope my problem will gone..
Also.. this was bad solution.. because I have 3 fieldset group.. and when page initialize - its init 3 times when each OnFieldSetExpand happens..
Thanks for attention
Denis