Filling asp:TextBox at FormNew.aspx

Question

I need to fill TextBox with parameter form QueryString. Code:

<asp:TextBox runat="server"  name="text1" id="ff1{$Pos}" text={$parameter}  __designer:bind="{ddwrt:DataBind('i',concat('ff1',$Pos),'Text','TextChanged','ID',ddwrt:EscapeDelims(string(@ID)),'@Title')}" />

                                <SharePoint:FieldDescription runat="server" id="ff1description{$Pos}" FieldName="Title" ControlMode="Edit" />

And I have problem. If Url is FormNew.aspx , TextBox is empy, I enter some value and save it. Everything allright. But when FormNew.aspx?parameter=somevalue, TextBox is filled, but i couldn't commit it to the list. Code of Button is standart:

<input type="button" value="Save" name="btnSave" onclick="javascript:{ddwrt:GenFireServerEvent('__commit')}" />

I have no idea why it is so. Plz help!