Keyboard V not functioning within Launchbox MAME

[sdmf392]

My P1B2 is mapped to the keyboard "V" with an Ultimarc and works fine natively in MAME and tested in other programs as functioning.  If I run any MAME game within launchbox this key ceases to function.  Any ideas?

Edited 2 hours ago by sdmf392

[JoeViking245]

That's an odd mapping for that button (vs. the default binding Left-Alt). 

In LaunchBox, edit you MAME emulator.  Look at the Default Command-line Parameters.  If it has -keyboardprovider dinput in it, try remove that.  If it doesn't, try adding it.

[sdmf392]

I've done a bit more troubleshooting and it appears that what I have wired should indeed be left alt since it's port 1SW2 on the ultimarc IPAC4, but when I press the corresponding arcade pushbutton it encodes a "V" to the PC.  I ran across a thread that said older boards might not be compatible with win11, but all the other functions are working and it is sending valid key presses to the pc so I see no issue there.  I've tried putting it to another port on the IPAC at 3SW4 which made the keypress "o", but the same problem happens where native MAME works fine, but launchbox will not send the command.  The -keyboardprovider dinput was indeed in my command line parameters so I tried to remove it but that didn't work at all.  What's interesting is if I push left alt on my keyboard it will do the correct function in launchbox mame, but I have removed that input assignment through the native MAME's settings.