Becker 7929 Not found on laptop when connected with usb cabl

Hello All

First post, so hoping you can help.

I've an older becker 7929 but when I connect thye usb cable the laptop recognises the device but only as a removable disk and when I explore, I can onlky see the contents of the sd card which has the maps and sounds.

I'm trying to update the maps but the installation programme is showing as no devise found.

Can anyone help me get the becker device to be recognised on my laptop soi I can update the maps.

I've checked the CE part and the settings are set for usb connection to a pc, so not sure what's going on.

Many Thanks in advance.