Android: String from strings.xml not showing when using (R.string.id)

Android: String from strings.xml not showing when using (R.string.id)

I'm trying to call a string from my strings.xml, this one:
<string name="before">I have read and understood the</string>
I use this line to call the string:
String append1 = getResources().getString(R.string.before);
I get "before cannot be resolved or is not a field", but if I use another
string from the same file it works just fine. You know if you type
"...(R.string." you get a list of available strings to choose from, and
some of my strings aren't showing in that list. How come?