Not enough input arguements .bin files

I am trying to open .bin files and import them so I can process them via EEGLAB but I keep getting a "not enough input arguments" error for line 18 of my script. The three asterisks are where I omitted file naming info. Running the function either gives me the input arguments answer or tells me that the files do not exist.

function datacheck

subjects={'317731_1_22072017_1139','317731_122072017_1251','316750_1_15072017'};

n_channels=[8,8,32];

dir_in = '***';

for s=1:length(subjects),

filename= [subjects{s} '.bin'];

nchan= n_channels(s);

filename= fullfile(dir_in, filename);

if exist (filename)~=2,

error([filename 'does not exist'])

end

end

return

The specific error message is this

Not enough input arguments.

Error in datacheck (line 18)

if ~isa(data, 'iddata')

If anyone knows what may help, please let me know!

[Jan]

The function datacheck you have posted, does not contain 18 lines. The failing line

if ~isa(data, 'iddata')

is not included in the code also.

Please show use the failing code.