Keylogger(Stream Writer) Is Not Working On Windows 8.1

I want to share my problem with you, i developed a key logger in c# console based and windows form also its working fine,and also using stream writer to write a text file with keys. i am using it on windows 7.8 and when i am moving to windows 8.1 then it partially blocked, exe is running but not write keys to text, means we can say stream writer is not working on windows 8.1

when i use my exe it was working sometime(When I make) but after around 1 hour stream writer not write keys in the text file. my code/exe is f9 bcz i have tested it on windows 7,8.its working any alternative of stream writer which i use on windows 8.1? Pls suggest me...