Lesson 23 Homework : cannot find symbol method ToLowerCase()

Whenever I try to use the method ToLowerCase() in a String variable I receive this error.
This happened before or am I doing something wrong?

Question.java:5: error: cannot find symbol String line = inStr.ToLowerCase(); ^ symbol: method ToLowerCase() location: variable inStr of type java.lang.String 1 error

Not a big problem, Try to replace your ToLowerCase() by toLowerCase().