Participant exclusion and participant agreement

#1
For those excluded in a study, if participants are unwilling to participate, they would be deemed not being in agreement to participate, however if participants are unresponsive after screening and are excluded because of this, is this considered not agreeing to participate, even though they didn't verbally say so? In other words, people who are unresponsive are classed as "did not agree" to participate. This makes sense, as someone who is excluded due to illness, occupation etc may have agreed to participate, but they didn't meet the criteria anyway. I thought I'd double check so I can accurately calculate the percentage of those who agreed to participate.
 
#2
If you screened the participants, they agreed to take part, and then failed to respond then I don't see why you should class that as not agreeing to take part. I guess it depends on the specific situation but it's very common to exclude people "due to non-responding".