You have 4.3E as internal BIOS and run a maxflash cartridge.
Oh, ok, I forget.
The 4.3E has higher priority over the 3.5F in the external cartridge.
But that is no issue, since 4.3E and 3.5F are compatible except for 1 thing.
3.5F supports 8 partitions defined by FDISK, were as 4.3E only supports the first 3 (!) entries in FDISK.
So it should work.
When you enter FDISK, do you get a HD-error?
(Hold BASIC and bootup, type BYE enter)
Later,
Sijmen.