Warning: Unsuccessful read: Matching failure in format.

hi all , i'm getting this error whentrying to read serial data send from arduino in matlab

    clear all
    close all
    clc
    % create serial communication object on port COM14
    arduin=serial('COM14','BaudRate',9600); 
    fopen(arduin); % initiate arduino communication
    % You must call TIC without an output argument before 
    % calling TOC without an input argument.
    tic;   
    % data va recevoir le type de mesure
    while (toc<=20)  % stop after 20 secs
       data = fscanf(arduin,'%f');
    end
    fclose(arduin); % end communication with arduino

thanks

[Jan]

Please post the complete error message and mention, which line causes the problem.