Specifically, it looks like both your X and Y arrays have a 0 as their first element. Is this data you read from a file, or something that was read from an instrument/DAQ, or something that you generated programmatically? If it's read from a file you may have a bug in your file-reading code.
Thanks for the suggestion and reply. I have managed to solve the problem by removing the 1st row of my array which previuosly written with some strings.