Loop over all labels in label file

I try to get   all label in certain label file, I try to use the function Microsoft.Dynamics.Ax.Xpp.LabelHelper::GetAllLabels , it returns only 500 labels even it has more than this number 

I try also the function Microsoft.Dynamics.Ax.Xpp.MetadataSupport::GetLabelFileContentStream, I face an error during the calling of the function , how can I get all label ids in label file ,also is there  a function to get the list of label files in the system ?