alt_signaltap_run giving Assetion fail in MATLAB

When alt_signaltap_run is run under MATLAB™, an "Assertion failed"pop-up window is displayed and MATLAB crashes when the pop-up is dismissed when i write this in Matlab:

addpath(('C:\altera\14.1\quartus\bin64'))

alt_signaltap_run

I am using MATLAB R2011b and Quartus II 14.1 (64-bit).