Just checked your app, My computer companion. I see the place for the AdMob to appear but it is blank. I'm in California. Also, perhaps your app is not finished yet, but the information screen shows up as white text on a light white background on my DroidX. It is not readable.
I don't get any ads. I'm in Israel. AdMob does work here properly.
I also got an error about a missing file: dos20.txt.
I recommend you to make the TabHost size 100%x and height 100%y - 50dip (for the ad). This way it will resize to the whole screen. I've tested your application with a tablet (Samsung 10.1) and it only uses a small portion of the screen.
I've just tried the following code and it works correctly.
B4X:
Sub Globals
Dim TabHost1 As TabHost
Dim ListView1 As ListView
End Sub
Sub Activity_Create(FirstTime As Boolean)
TabHost1.Initialize("TabHost1")
ListView1.Initialize("ListView1")
Dim p As Panel
p.Initialize("")
TabHost1.AddTab2("Tab 1", p)
p.AddView(ListView1, 0, 0, -1, -1)
ListView1.FastScrollEnabled = True
Activity.AddView(TabHost1, 0, 0, 100%x, 100%y)
For i = 1 To 4000
ListView1.AddSingleLine(i)
Next
End Sub
Resize them? They've fallen off the bottom of your screen, but I'm sure you knew that already. I would make the OS items and text a little smaller and they should all fit. Then again the hints text needs to be a bit bigger, imho.