How to ask my professor to write recommendation letter for me?

Now I'm in a community college and I am trying to gathering recommendation letter to apply to graduate school.(I have already got my bachelor degree). I performed well in calculus and got an A in that course. After i got my grade, I wrote a thankful email to my professor and he replied me that I am the top student in his course. I thought he is nice. Therefore I asked him whether he can write me a recommendation letter to me by e-mail but there is no-reply. I considered if he didn't see my email, so I went to his office and wanted to see him in his office hour. His office hour was posted on the wall and on the schedule he said if anyone want to see him please notice him ahead of time. So I e-mail him again to ask for an appointment. Here is the content:

Dear Prof XXX:

        It's XXX, a student who finished your calculus 1 last semester. I 

went to you office yesterday and record your office hour on the wall. Would it

be possible to meet with you next Monday 11 am (office hour) about whether you

can help me write an recommendation letter?

Regards

He didn't reply me. I almost lost my confidence. I don't know whether I need to

go to his office directly. I am afraid it's impolite or disrespect. And I don't

know if he don't want to do it, why he praise me in the first thankful note?

Hope anyone can help me.