I have two NB and all installed IDE 1.6.8. One of NB to open sample of MultiSerial and verify complete but another one get error message "In function 'void setup()': MultiSerial:27: error: 'Serial1' was not declared in this scope". I'm very confuse why have this kind of symptom. Is is any install problem of IDE or something miss in Win7 pro OS?
MultiSerial_error.doc (31 KB)
What's NB ?
Try an older version of the IDE. I have 1.6.6 running on Windows 8 and Windows 7; some people swear by the latest release of 1.6.5.
It's still the same with 1.6.6 and 1.6.5 r5 IDE. One question, is it have to connect MEGA board to verify code? I didn't connect any Arduino board to check.
No, you can compile (verify) without a board being connected. But you must select the correct board ! If you select an Uno (your output indicates that), the compiler does not know about Serial1.
I still don't know what NB is 
And please add error messages in the post, not as an attachment and definitely not as a stupid Word document. Use code tags to post code or error messages.
[code] your code or error message [/code] will result in
your code or error message
Sorry, it's my mistake not change as MEGA board. It's solved. NB is Notebook. Thank you.