In response to the OP you should be using the integrator (round diffuse piece of plastic) under the lens of the enlarger if you are not already, for both slides, and do as you have done, but note that the exposure knob should always be set at the time you used to make your print, and do not move the probe after zeroing the meters. Also, there is a special filter that should have come with it that you place over the probe for slides. It is not needed for negatives. If you do not have it, results may be off. For the slide you want to print, push the cyan button and zero the meter by changing the aperture on your enlarger lens, not the cyan control on your enlarger. Then push the magenta button and zero the meter with the magenta control on your enlarger, then push the yellow button and zero the meter with the yellow control on your enlarger. Repeat for each channel until the readings stay at zero. You now have the filtration in your enlarger to make your print. Now, depending on the nature of the slide you may have to reverse the procedure for the cyan and magenta channels if you can't zero the readings. Good luck.