Files added to gitignore but it still tracks those files

Question

I am using following in my .gitignore but it is not ignoring log files and dll files. Can someone explain me what I am doing wrong.

 Debug/
*.vcxproj
.vs/Projects2010/v16/.suo
*.db
*.db-shm
*.db-wal
*.opendb
*.vcxproj
*.cache
*.obj
*.recipe
*.log
*.tlog
*.bsc
*.lib
*.pdb
*.idb
*.dll
*.sbr
*.pch
*.res
*.exe
*.ipch
*.ilk
*.ilk
*.exe