The histogram function is primarily for plotting histograms. As described in that documentation, the output you are getting is the object handle to the histogram. The reason for the 'Invalid or deleted object' message is that because you do not create new figures for each histogram, each one is getting overwritten (and therefore deleted) by the prior one.
It sounds like maybe you actually need the histcounts function instead. That should give the values you need. I suggest you carefully read that documentation, to understand the output you'll be getting.
