[Freesurfer] annot 2 label file conversion

Hi there, I've some troubles with parcellisation schemes. I've used mri_annotation2label to extract labels within annot file. When I read the annot file within matlab (read_annotation.m), I found 869 entries, everything looks good so far. However, when I look at the output directory of labels, I only found 770 label file. For another parcellisation scheme, I found 325 entries in annot file and 496 label files... These findings are consistent across several subjects. So my question is how mri_annotation2label processes annot file? and how to find correspondence between annot and label files? Any advice would be greatly appreciate,