1) Welcome to the Party!
2) As you are obviously new here, I have some suggestions to help us all help you:
When you post, please post your entire configuration including (but not limited to) your installation method and vicidial version with build.
This IS a requirement for posting along with reading the stickies (at the top of each forum) and the manager's manual (available on EFLO.net, both free and paid versions)
You should also post: Asterisk version, telephony hardware (model number is helpful here), cluster information if you have one, and whether any other software is installed in the box. If your installation method is "from scratch" you must post your operating system and should also post the .iso version from which you installed your original operating system. If your installation is "Hosted" list the site name of the host.
If this is a "Cloud" or "Virtual" server, please note the technology involved along with the version of that techology (ie: VMware Server Version 2.0.2). If it is not, merely stating the Motherboard model # and CPU would be helpful.
Similar to This:
Vicibox X.X from .iso | Vicidial X.X.X-XXX Build XXXXXX-XXXX | Asterisk X.X.X | Single Server | No Digium/Sangoma Hardware | No Extra Software After Installation | Intel DG35EC | Core2Quad Q6600
3) Usually because you have "bad numbers" in your dialer. No match to a dial pattern. The first line in the Carrier's (Admin->Carriers) dialplan entry is a line with "AGI" in it. This initiates a script that attaches Vicidial to the call. If the dialed number does not match a carrier entry, then this line never executes. And Vicidial will never change the status of that lead (that Vicidial never saw ...). So add an "s" extension to one of your carriers with JUST that AGI line and a Hangup line (don't bother with the dial command) to clear them out.
4) Try locating and dialing one of those numbers manually. Post the asterisk output here from the attempt if you don't find the problem.