A great business doesn't always translate into a great stock.Shares of Shopify (SHOP 1.02%) have risen more than 20% this month as investors have been encouraged by the company's strong growth in revenue and gross profit. But investors shouldn't get too excited. There's good reason to believe the stock's recent rebound could be hot air.Sure, the e-commerce platform company continues to execute well and management seems to be making a lot of good decisions. The problem, however, is the stock's valuation -- t ...