Co-working spaces are a dime-a-dozen these days. There's no shortage of co-working spaces. Without knowing exactly what sets yours apart from all the rest my only assumption is that the product your providing (co-working space) isn't good enough to convert. On the other hand the issue can be with your pricing as well, not only level but also contract duration etc. Try really hard to think about why a company should choose you as opposed to the numerous other alternatives.