The 'INF' text is returned as an error when you try to do something like divide a number by 0 (INF is short for infinity).
The errors are from trying to process the text 'INF' instead of an expected number.
There could be a few reasons for this. You might be asking for statistical results (Cp, Cpk, ...) which would require a valid tolerance, a minimum number of subgroups, actual measurement data (empty cells are ignored), and so on.
