Thanks for reaching out to the Apple Support Communities, smheman!
It sounds like when you make a custom label for a contact, you're unable to make an outgoing call to them from the contact. Check out these steps to Update your iPhone, iPad, or iPod touch and be sure you’re running the latest software version available for your iPhone. Also, follow the steps in this article for How to force an app to close on your iPhone, iPad, or iPod touch and quit the Contacts app. Once it’s closed, Restart your iPhone.
Does this happen when you use the standard Phone label for the contact (i.e. mobile or iPhone)? Does this happen with all contacts or with a specific one?
Let us know the results and have a great day!