I am registering in a site ..At the end of registration in 'Image Verificatiaon' system asked to enter the six digits that are displayed in the image ....I entered the correct digits as shown by the system and clicked on Register

System displayed the error as ' Incorrect digits entered' ..Please enter the six digits that are displayed in the image...

What would be the issue that this error message is displayed though correct digits are entered..Pls do not say that i might have entered the wrong digits..I have entered the correct digits but still the error is displayed..What would be the reason ?