text() in Matlab

when i use this code in Matlab,

text( x, y, 'N', 'Color', 'r');

i get an annoying error

??? Error using ==> text

Invalid parameter/value pair arguments.

finally i found answer on the web,

it is because x is a integer, it must be double.

then i convert x into double class, then it is ok,

damn machines and thank google