Social ties have been hypothesized to help people to gain support in achieving collaborative goals. We test this hypothesis in a study of organizational crowdfunding (or "crowdfunding behind the firewall"). 201 projects were proposed for peer-crowdfunding in a large international corporation. The crowdfunding website allowed people to join a project as Co-Proposers. We analyzed the funding success of 114 projects as a function of the number of (Co-)Proposers. Projects that had more co-proposers were more likely to reach their funding targets. Using data from an organizational social-networking service, we show how employees' social ties were associated with these success patterns. Our results have implications for theories of collaboration in social networks, and the design of crowdfunding websites.