[FFmpeg-user] Can't locate entry av_aes_crpyt in avutil-49.dll

[Erik]

I just start to write some application using FFMPEG, the application itself is 
OK but before it start running I got this error message
I think I may have a incompatible version of avutil-49.dll...I download FFMPEG 
dev packet here(it seems doesn't include those DLLs)and I download the 
avformat-52.dll, avcodec-51.dll and avutil-49.dll. At least it seems no error 
in avformat-52.dll, but the avutil-49.dll get wrong
My avcodec-51.dll: 6,212,096 bytes
avformat-52.dll: 713,728 bytes
avutil-49.dll: 19,968 bytes
I even downloaded a avutil.dll(57,344 bytes)and tried to rename it to avutil-
49.dll but it still error at different entry. How to get the correct DLL? I'm 
sorry I don't know how to use tools like msys at all so don't just tell me to 
compile FFMPEG myself thx