edit control in IE5 can't use backspace, cursor keys

Hi,
I have an ocx (with two edit fields) running in the testcontainer and all keys work.
If I use the same in IE4 or IE5 the backspace and the cursorkeys don't work. The
backspace acts like the BACK Button in IE. But if I press TAB then backspace works. If I
press TAB once again it highlights the URL-line. Then I can use the mouse to click in
the editfield and now all keys work.
Is there a possibility to use all keys without pressing TAB-TAB and activate with the mouse
TIA Marco