Every time I think I know how to do things right, something throws me off.

I dont see anything at all wrong in your approach. Email might have went to spam, she might be on hiatus, might have deleted it by accident, who knows.

If she is available and wants to see you she'll let ya know.

If I was managing them, I wouldn't be asking questions.

Some things seem so logical to me, but turn out to be the wrong thing to do, at least in this realm

You keep asking your questions and we'll do our best to help you out. There is quite a lot to learn about this biz and this is the place to do it.

How hard can that be to arrange?

It is not at all unusual that you got no reply. Getting in the door is difficult at best. Being that you aren't local and were trying to set something up on a "maybe" in the future didnt help your cause.

We can receive many requests in a day.

...in the loop.  Also, you generally aren't dealing with the provider herself.  Most K-girls have bookers who handle their appointments.  If the guy who referred you is an approved K-hobbyist, he can call the booker and put in a good word for you.

Ms Smith makes a good point. When I'm doing something similar, I PM (or do a pre-verify request,) through P411 so the lady can see my profile, okays, etc.  I'll also see if and when she reviews my profile as the site pings me whenever the profile is reviewed.  If you're only doing a PM, then you'll need to include your P411 ID in the PM,but if you're doing a pre-verify or appointment request, that info gets imbedded in the message sent to the lady.  

P411, told me that about 50% of ladies don't actually read your profile there after you request a date. I don't believe that they are actually logging into the site which pushes them down the list costing them potential clients. I guess they aren't even slightly curious about the guy that is coming to meet them.  

or be "juiced" into the loop by a guy already in the system as BPS has suggested.

In many cities, the K girls have started becoming more mainstream and even advertise on sites like P 411 and accept that for screening, but in many cities LA and DC are a couple that come to mind, getting screened the first time can be challenging.

They may not read your profile, but in most cases will see at least the number of OKs.  In my situation I started whith P-411 with their free six months and now have multiple OK's. As an older white male have not had a refusal for a date. More than one provider has not shown up as reading my profile but knew that I had X  OKs. I have only recently have signed as a TER member and as of now do not have of my P-411  providers whitelisting me but would guess that with the same number of white lists the result would be the same.  I in your own community and you have whitelist they may not need a formal reference as they may beclose friend of your last visit or know that Povider x is careful and does not give OKs or white lists lightly. Comfort!!

apparently some of the above responders do.  Were you approaching a non-K-girl, your message might have gotten some attention.  However, a little more info (for screening) from you might have been appropriate.  You really didn't give her much to go on.  I realize your travel plans are not set in stone far ahead of time, but if you are going there for medical treatment, it seems to me that you might know a little ahead of time when you were going to be in her city.  Giving a more specific time frame, date and time of day, would go a long way in letting her know you are not just another time-waster.

I'd thought afterward that not providing full screening information may have been the reason for not getting a reply. I didn't know that the K girl community could be so closed.

Sorry Dude, but it's the "if" that made her press delete. She responds to emails that she knows are going to be appointments. All time is money after all. Next time put it into short, Positive language i.e. "Hi, I'm ____,I'm coming to your town and I REALLY want to see you. Here is all my info so you can prescreen me, (TER name, P411 #oks, DC # verifies) I come on short notice so I want to be prescreened in advance. Please. Then you can go into who referred you, but she may not even read it. Just my 2 cents.

and am I missing something?  From my basic research, it seems as if they're 'just' Korean girl providers?  What make them different to warrant a whole 'world' of their own. I guess I'm a newb on this one!

The rewards are well worth it.

Or to put a finer point on it, K-girl agencies expect you to follow protocol to the letter. If you don't come absolutely correct you'll get no response.