How to solve "Matrix dimensions must agree error" for this function?

Matrix Dimensions didn't agree in a function. Please tell me the meaning of unique function. While i try to debug the function by setting breakpoints, the trblock cell array receives value only in the 1x6th location, it actually has 1x8 cell array, all other locations are empty. and the tr_block_diag_mat has 15x15 single value

my values are tr_descr = 114x98, tt_descr = 112x98, tr_label = 114x1, tt_label = 112x1, tottrainlabel = 231x1

Error in ProCRC (line 34) tr_sym_mat = (gamma * (class_num - 2) + 1) * (tr_descr' * tr_descr) + gamma * tr_block_diag_mat + lambda * eye(size(tr_descr, 2));

%%Function
function Alpha = ProCRC(data, params)

tr_descr   =   data.tr_descr;
tt_descr   =   data.tt_descr;
tr_label   =   data.tr_label;

gamma      =   params.gamma;
lambda     =   params.lambda;
class_num  =   params.class_num;
tt_num     =   length(data.tt_label);

model_type =   params.model_type;

tr_blocks = cell(1, class_num);

for ci = 1: class_num
    tr_blocks{ci} = tr_descr(:,tr_label == ci)' * tr_descr(:,tr_label == ci);
end

tr_block_diag_mat = blkdiag(tr_blocks{:});
tr_sym_mat = (gamma * (class_num - 2) + 1) * (tr_descr' * tr_descr) + gamma * tr_block_diag_mat + lambda * eye(size(tr_descr, 2));

%%Main program
data.tr_descr  = F_train';
data.tt_descr  = F_test';
data.tr_label   = otrainlabel;
data.tt_label  = otestlabel';
dataset.label = tottrainlabel;
% class_num = length(unique(dataset.label));
class_num = length(unique(data.tr_label'));

params.gamma     =  [1e-2];
params.lambda     =  [1e-0];
params.class_num  =  class_num; 
params.dataset_name = 'Action';

params.model_type =  'NN';

Alpha = ProCRC(data, params);

[KSSV]

Problem is here in this line:

tr_blocks{ci} = tr_descr(:,tr_label == ci)' * tr_descr(:,tr_label == ci);

This is resulting into a empty matrix and creating problem. check that line once.