Enter Key submition is not raising the command event

[Jitu]

<form runat=server id=myform>
<AT_COMMON:Site Page id="DefaultPage " runAt="Server">
<itemTemplate >
<AT:UsersRegist ration id="Registratio n" RunAt="Server"
UserFormName="U sers/Users/UserForm.ascx"
SkinFileName="U sers/Users/UserRegistratio n.ascx" />
</itemTemplate>
</AT_COMMON:SiteP age>
</form>

Above is the hirarcy of my controls in the form.

1] In the control AT:UsersRegistr ation there is one control again
UserForm.
2] The AT:UsersRegistr ation has submit ('_submit') button and cancel
('_cancel') button.
3] I want to fire the _submit_command event while user submits form
using enter key. The Form gets submitted but, the event is not fired.
4] I've registered default command using
Page.RegisterHi ddenField("__EV ENTTARGET", "_submit")

Now See the difference in below hirarchy.

<form runat=server id=myform>
<AT:UsersRegist ration id="Registratio n" RunAt="Server"
UserFormName="U sers/Users/UserForm.ascx"
SkinFileName="U sers/Users/UserRegistratio n.ascx" />
</itemTemplate>
</form>

1] the event gets fired in enter key submition.

=============== =

Can anyone help me on this?

Thank you.

Jitu