If you pass LAME a file with a samplerate of 22KHz it will attempt to use MPEG 2 Layer III, which has a maximum bitrate of 160kbps. Here's the output from LAME on the command line:
CODE
MPEG-1 layer III sample frequencies (kHz): 32 48 44.1
bitrates (kbps): 32 40 48 56 64 80 96 112 128 160 192 224 256 320
MPEG-2 layer III sample frequencies (kHz): 16 24 22.05
bitrates (kbps): 8 16 24 32 40 48 56 64 80 96 112 128 144 160
MPEG-2.5 layer III sample frequencies (kHz): 8 12 11.025
bitrates (kbps): 8 16 24 32 40 48 56 64 80 96 112 128 144 160
fatal error during initialization
If you really want your file as 320kbps, although given the quality I don't know why, you should apply resampling before conversion, by checking the DSP checkbox on foobar's Converter dalogue, and selecting "Resampler (PPHS)". Obviously resampling to 44100Hz is adequate - but you'd need someone who knows what they're talking about to say whether you would do better to use 48000Hz, for example.