Could not load texture

Question

What I want is to load a picture in the Panda3D, but it can't run for the reason of could not load the texture. I really don't know why for the code could run well in the other environment.

def run(self):
    base.win.setClearColor((.49, .49, .49, 1))
    pic1 = -1
    block = 1
    trials = 0
    nc = 0
    homescreen = self.picture('Guide.png', duration=0, scale=(1, 1), pos=[0, 0], block=False)
    self.waitfor('space')
    homescreen.destroy()

This is the error information:

File "modules\Exp2test.py", line 24, in run homescreen = self.picture('Guide.png', duration=0, scale=(1, 1), pos=[0, 0], block=False)

IOError: Could not load texture: Guide.png