Action if checksum did not change

Hi,

I try to make a test to check if a checksum changed. I expect it to 
change in normal conditions. If it does not change (but timestamp may be 
updated), it's a fail.

I am a bit confused with the manual:

> Check specific checksum:
>
> |IF FAILED [MD5|SHA1] CHECKSUM [EXPECT checksum] THEN action|
>
> Check any file changes:
>
> |IF CHANGED [MD5|SHA1] CHECKSUM THEN action|

I tried this:

if changed checksum then exec "/bin/true" else alert

But I get an error on the "else".

Now I use this:

if failed checksum then alert

but not sure if it's the right way to do that. The confusing part to me 
is to have a fail about an optional |[EXPECT checksum]| value.

Any idea how I could do that ?

Thanks for your help.

Btw I take a lot of pleasure to make ton's of working tests!

Read you,

Jej