Cannot encode stream using x264enc

[William Metcalf]

I have a pipeline I am using to convert an .ogg file to an .mp4.  I am 
currently using ffenc_mpeg4 to encode the video, and this encoder sets 
the video format as .mp4v.  I need my video to be encoded as AVC so I am 
trying to use x264enc instead.  However every time I try to use x264enc, 
I get the error "failed to encode stream".  Below is a sample pipeline I 
am using in my converter.  Can any one tell my why x264enc is failing to 
encode the stream?  Thank you in advance.

gst-launch filesrc location="c:\\video(low_res).ogg" ! oggdemux ! 
theoradec ! ffmpegcolorspace ! x264enc ! qtmux ! filesink 
location="c:\\video(blah).mp4