I outlined it in one of my last posts but my opinion as to why the share price has not been lifted by short covering is that the roughly 600k short term shorts were covered by shares obtained through buying investment units in the latest offering.

For a company like RVX it is a very good trade to short the shares upon news of a financing, when the price is usually high, and use the proceeds to by investment units. When the offering is settled you then strip out the shares to settle the short position and keep the warrants. This keeps the actual cost of the warrants very low and allows you to settle the short position on a low volume stock without driving the market, and your cost, higher to settle the position.