error in matlab function block

• Item one
• Item twoi am using a 'matlab function' block i write the code to map a file to memory using this instructions

filename = fullfile(tempdir, 'talk_answer.dat');

m = memmapfile(filename, 'Writable', true, 'Format', 'double');

 j=m.data(1:5);

i have an error in "j=m.data(1:5);" this error appears " Attempt to extract field 'data' from 'mxArray'. Function 'MATLAB Function' (#23.1222.1223), line 43, column 4: "m" Launch diagnostic report."

what can i do to avoid this error

[Geoff Hayes]

Prior to executing the line j=m.data(1:5), type the following in the Command Window

 disp(m)

What is written to the console? Please paste the results to a comment. As well, please include your version of MATLAB.

[wael taie]

m = Filename: 'C:\Users\WAEL_T~1\AppData\Local\Temp\talk_answer.dat'

    Writable: true

      Offset: 0

      Format: 'double'

      Repeat: Inf

      Data: 32x1 double array

my matlab version :R2012b.(8.0.0.783) win64

[Geoff Hayes]

What happens if you just run the following test code

 myData = double(1:10)';
 filename = fullfile(pwd, 'records.dat');
 fileID = fopen(filename,'w');
 fwrite(fileID, myData,'double');
 fclose(fileID);
 testVar = memmapfile(filename, 'Writable', true, 'Format', 'double');
 k=testVar.data(1:5);

It will create a small file and then execute the same commands as before.

Also, type

 which m -all

I am just curious if your choice of variable name m is conflicting with something else.