How can i check if an address is valid or not?

Here is a sample you can try, hope it helps. I'm using Visual Basic 6 with the ActiveX Control on my form Named MPC. The ADDR, CITY, ST and ZIP would be your variables.

Dim objmap As MapPointCtl.Map
Set objmap = MPC.ActiveMap
Dim objloc As MapPointCtl.Location


Set objLoc = objmap.FindAddress(ADDR, CITY, ST, ZIP, geoCountryUnitedStates)
If objLoc Is Nothing Then
Msgbox "Can't find address"
End if

You can also use the FindResults property. Samples in the Help File