Your field names are wrong, and you should convert the values to numbers if you want to ensure numerical addition if either one of the fields is blank. You also need to set event.value to the result of the calculation:
var v1 = +getField("Value1").value;
var v2 = +getField("Value2").value;
event.value = v1 + v2;
You misspelled you fields' names. JS is case-sensitive, and also you added
an "i" in the name of the first field.
Also, if you're using this as a custom calculation script the last line
event.value = v3;
You have to use getField, not getfield. I had a typo in my original post that I corrected, so you may have seen the bad version. Sorry about that.
It is somewhat dorky that JS is case sensitive.
I never had this big of a problem coding in VBA !!!