There are two different limits: There is a daily limit for votes on posts, and there is a daily limit for votes on comments.
The limit on comment votes is reported on Comments: Now with Flags and Votes.
Each user gets 5 comment flag votes, and 30 comment upvotes, per day.
The error message could be misunderstood, and interpreted as saying that you cannot vote anymore on comments and posts.
Probably the message should report which daily limit has been reached. In that way, users would not take the assumption it means they cannot vote anymore for that day. The problem is when you have also reached the daily limit for post votes, and you think there is a daily limit for votes that includes both the votes on posts, and on comments. (It actually happened to me, and I thought I could vote for comments as long as I still had votes for posts to cast.)