Can’t extend cross dissolve in Final Cut Pro

I’m making a music video with final cut pro consisting of a foundation video clip that runs through out the video. And on top of that I insert cross dissolve video clips for effect. As a bonus I now wanted to add a new video clip featuring my vocals etc. No problem adding it, but I can’t seem to be able to make the cross dissolve so it blends with the other clips. When I insert cross dissolve it gets created, but I can’t drag it to make the fade longer. How ever I try to get the symbol showing to be able to drag it just doesn’t show…Is there a limit to how many clips with crossfades you can use? Any other helpful trick to get the newly added vocalclip to blend so the foundation clip and others show?

[Re-Titled by Moderator]

Original Title: Final Cut Pro cross dissolve