CC Not working with Pioneer VX 521 AV receiver

CC has been working intermittently with my Pioneer VSX 521 AV receiver. There are times when it starts up and immediately the red panel light which confirms that the hdmi connection is through lights up. At other times such as right now it doesn't work at all. For reference I have connected CC on the video hdmi input and the tv is on the hdmi out. Control via the hdmi port is switched off. Can anyone help Pl.