why "iconv" didn't convert myfile.csv to ASCII?

(it seems that this post is best put here, where shell programming people use "iconv" and "file" all the time. it was posted in the Linux Application and got no replies)

Dear there, I tried to use iconv to convert myfile.csv to ASCII and failed. Any ideas? myfile.csv contains only ASCII characters.

here is the log:
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sychen@sychen-laptop:/tmp$ file myfile.csv
myfile.csv: Bio-Rad .PIC Image File 13619 x 12339, 13618 images in file
sychen@sychen-laptop:/tmp$ iconv -f UTF-16 -t ASCII//IGNORE myfile.csv -omyfile_iconv.csv
iconv: illegal input sequence at position 16320
sychen@sychen-laptop:/tmp$ file myfile_iconv.csv
myfile_iconv.csv: empty
sychen@sychen-laptop:/tmp$ iconv -f UTF-8 -t ASCII//IGNORE myfile.csv -omyfile_iconv.csv
sychen@sychen-laptop:/tmp$ file myfile_iconv.csv
myfile_iconv.csv: Bio-Rad .PIC Image File 13619 x 12339, 13618 images in file
sychen@sychen-laptop:/tmp$ head -n 2 myfile.csv
353025450,AUD/JPY,2007-10-14 17:00:06,106.320000,106.390000,D
353025553,AUD/JPY,2007-10-14 17:01:23,106.330000,106.400000,D
sychen@sychen-laptop:/tmp$ head -n 2 myfile_iconv.csv
353025450,AUD/JPY,2007-10-14 17:00:06,106.320000,106.390000,D
353025553,AUD/JPY,2007-10-14 17:01:23,106.330000,106.400000,D
sychen@sychen-laptop:/tmp$ iconv --list

You start out by saying that your file contains only ASCII characters. If so, then why are you trying to convert it from UTF16 to ASCII?

by ASCII characters, I mean the ASCII range (U+0000 to U+007F)