Hi,
I am trying to put together a formula field (with HYPERLINK) that takes me to other URL. I am trying to pass 'Id' of the object - but for some reason, when I click on that link the new URL comes without the actual value, i.e. the parameters are not substituted with actual values. This is what I am doing:

HYPERLINK("/mail/mmchoose.jsp?retURL=%2F{!Id}&1={!ContractNumber} &id={!Id}", "Create Contract")

I am sure I am ignoring something very obvious, but I am unable to get it. Any help here would be greatly appreciated,

Thanks in advance,