Recoding Variabls in SPSS

I am having trouble recoding a variable that has been combined with data from another survey. A portion of the data is numeric , ("1" 1024... and the rest is "Definitely yes" 2100). I need to combine them so that the entire variable looks like this "Definitely yes 4201") I am going through the "recode into different variables" routine, when I put in the old value, SPSS will not even let me type in the "new value" dialogue box. any answers would be greatly appreciated