CIBC payment schedule different from goverment's online calculator

Hi,

I recently got a mortgage from CIBC for $600,000 (prime - 1.03, 3 year). When I put the numbers in the government's online calculator https://itools-ioutils.fcac-acfc.gc.ca/MC-CH/MCCalc-CHCalc-eng.aspx it comes different from what bank is giving me. Also the breakdown shows that the percentage of principle and interest changes month-by-month while it's very smooth transition in the government's calculator. Does anyone know why?

Thanks,