Who is my boss and where can I find him?

So, as I said in my first post I'm an administrative assistant/personal assistant/executive assistant/office manager at a small hi-tech company and though I accept my position in the company I sometimes feel clueless.

Admittedly, I'm not as clueless as I was when I started the job over two years ago. I'm also not as desperate to quit/find another job as most of the guys and gals over on http://savetheassistants.com/. Most days I even look forward to some part of my job.

The cause of my confusion? The company and my boss/bosses.

So, when I started I was led to believe that my manager/boss is the VP Operations (VPO) which made sense as I had a lot to do as an office manager (including two year's worth of back filing). I was also tasked with helping the CEO and COT which also made sense as I was the only administrator at the company.

Now, over time I requested and even got a few extra responsibilities that are actually more in the realm of an executive administrator and I was pretty content. I still reported to the VPO and managed to juggle all me tasks.

A couple of months ago when meeting with the VPO and raising some issues (so minor, I can't even recall what they were) he tells me that he isn't my boss and my boss is actually the CEO.

OK, I can live with that, I mean, all the managers at my company are great people and their treatment of me is really great. The drawback to having the CEO as my boss? Prepare yourselves...

He's not in the office (or available via cellphone or e-mail) enough.

I know some of you are going 'What the fuck? That's a problem in your world?' - well it is.

Let's take a hypothetical: say a contact of the CEO (CEO-C) is looking for the CEO. That's plausible and I have no problem prioritising and either giving CEO-C the cell phone # of CEO or e-mailing CEO that CEO-C called looking for him or whatever I deem appropriate. Again, not really a problem. The problem is when the CEO-C needs CEO by a certain deadline, I know that he is looking for CEO-C for something that can benefit the company is some way and CEO fell off the face of the Earth.

It happens. A lot. I actually got yelled at by a couple CEO-Cs and I can tell you that at that point my day is ruined and I'm thinking of finding some other place of employment.

What's that to do with feeling clueless? I don't know what to do in this situation and that causes to feel clueless every month or so.

Also, whenever he is at the office he all the R&D people clamoring for his time and I feel really lucky if I can a few minutes of quiet with him and get him to sign all the documents that need to be signed etc. I don't feel like there is room for me to raise any issue I have since the R&D people need his feedback or decision so they go ahead with the product and since that's going to be the livelihood of he company...