You should tag the number of the destination screen to the LOAD IFF command like this:
X> Load Iff "filename", number
Can't open narrator (185)
AMOS Professional is unable to find "narrator.device" in the current "devs:" directory, so the
narrator program cannot be loaded.
Can't resume to a label (4)
You cannot use RESUME label inside an error procedure.
Can't set dual playfield (70)
The screens you are using are not suitable for setting up a dual playfield. The correct screen
combinations are explained under the DUAL PLAYFIELD section of this User Guide.
Command not supported by device (143)
This error is returned by the DEV DO and DEV SEND commands. A command has been sent
that is not supported. Check with Commodore's documentation.
Copper list too long (77)
The user-defined copper list has a pre-set limit of 12k. This may be extended using the [Set
Interpreter] option from the [Config] menu.
Copper not disabled (76)
You are not allowed to use the COP MOVE or COP SWAP commands before disabling the
normal copper list with COPPER OFF.
Device already opened (140)
You've tried to open the same device twice. The PRINTER and PARALLEL devices can only be
opened once in any particular session. If you're using multi-tasking, check that another
application hasn't grabbed the device first. If so, you'll have to quit from the application before
running your AMOS program.
Device cannot be opened (142)
The selected device cannot be opened for use. Make sure that it's correctly connected, and that
the appropriate device drivers are available from the DEVS folder of your current start-up disc.
Device error (144)
A device has reported a device specific error. AMOS Professional cannot keep all possible errors
in memory so check with Commodore documentation for the correct error meaning.
Device not available (86)
You have specified a disc or a drive, but your Amiga does not believe that it exists, possibly
because you have changed a disc unexpectedly. You can set the directory to the correct drive
name with an instruction such as:
X> Dir$="Df0:"