Handling Errors from COM components

I have some problems handling Errors returned after invoking a
COM/Automation object.

I read the "Sapiens TFM" sample chapter (which explains things quite
clearly I thought) but I am missing something

I would be happy with the original error text, plus the script
terminating. However, here's what I see:

I have a dev.ps1 script that defines a global function, which creates
an Automation object, passes this to a local function, which uses it.
The following happens if the call on the Automation Object returns an
error:

(1) Without "trap", poweshell displays an error (location of call, and
error message from Automation object). Very useful! Unfortunately, the
script continues with the next command

(2) A "trap" added to the top of the script file gets never called.
Same Behavior as under (1)

(3) A "trap" added to the actual function calling the COM object gets
called, but the $_ object seems empty. neither Write-Host $_ nor
Write-Host $_.Exception.Message display anything. However, I could
"Throw" here to terminate the script, but this displays no helpful
message.

Any ideas?

Trap {
Write-Host "ERRORINNER"
Write-Host $_.Exception.Message
Throw
}

thanks!