An error occurred while creating the mad build for the gstreamer library.

An error occurred while creating the mad component in the gstreamer library-general Linux technology-Linux technology and application information. For details, refer to the following section. After mad build is installed, the libstmad. a libstmad. la libstmad. so file already exists in/usr/locate/lib/gstreamer-0.10/
$ Gst-inspect mad
The relevant plug-in information is also output.

Factory = maid ("mad ");
Factory is null.

Similarly,

Element = maid ("mad", "decoder ");
Element is null.

In
Source = maid ("filesrc", "file_source ");
No error is reported.

I don't know what the problem is?

Thank you very much for your help.