kappaetc kalpha krippalpha

Hello - I am trying to calculate interrater reliability for 5 raters (always the same) for 5 students, on 6 items, using an interval level of measurement. I have tried all of these using my data and keep getting very different results. kalpha seems to give me something that meets the "uh huh" test and it is giving moderate strength results which the eye test agrees with. But then I run kappaetc and the kalpha coefficient is not the same was when I use kalpha. Then I tried krippalpha and it is different again. I am not sure if someone can assist... Thanks