How do I enter the code?

I have recently bought a 1999 Renault kangoo van with a blaupunkt cassette radio fitted - it has Renault printed on it but no stickers or model numbers or anything (been peeled of by the look of things).
I have the code written on an old service document but can't work out how to enter it - the display shows ---- and the "AF" symbol is flashing.

HELP!