MP3 variable: part2_3_length, What to do when it is zero. Options

[lyfzabytch]

Hello all,
I am making a MP3 decoder in Matlab for my bachelors' final year project. I am using a test mp3 file in which part2_3_length of first 3 frames is zero. Now I have written code after header and side info extraction which depicts the following pseudocode :

if( part2_3_length == 0)
increment a variable (this variable has nothing to do with the problem )
else
extract scale factors and huffmann data.
end

now what happens is that in all frames the 'extracting scale_factors and huffman data' part is skipped because of the part2_3_length...what should I do?
Plz help.