not getting the brightness values

[sandeepecpl]

not getting the current and max value for Del Monitor (D1918H) connected with HDMI.
But is working good with VGA Cable (using Thunderbolt VGA Adapter)
the following is the log messages I got

ddcctl -d 1 -b ?
D: CGDisplay 11DF0DF5-B394-D7B2-509C-70105C94E919 dispID(#721944898) (1366x768 0°) 85.00 DPI
E: Failed to parse WindowServer's preferences! (/Library/Preferences/com.apple.windowserver.plist)
I: found 1 external display
E: Failed to parse WindowServer's preferences! (/Library/Preferences/com.apple.windowserver.plist)
I: polling EDID for #1 (ID 721944898 => (null))
I: got edid.serial: 2C8FJ88A8TPE
I: got edid.name: D1918H
D: action: b: ?
D: querying VCP control: #16 =?

D: IOI2CNoTransactionType supported
D: IOI2CSimpleTransactionType supported
D: IOI2CDDCciReplyTransactionType supported
D: IOI2CCombinedTransactionType supported
D: IOI2CDisplayPortNativeTransactionType supported

D: IOI2CTransactionTypes: 0x1f (31)
D: IOI2CNoTransactionType supported
D: IOI2CSimpleTransactionType supported
D: IOI2CDDCciReplyTransactionType supported
D: IOI2CCombinedTransactionType supported
D: IOI2CDisplayPortNativeTransactionType supported
Request result = -536870206
E: No data after 10 tries! (1ns reply-timeout)
2021-02-19 21:04:35.279 ddcctl[3693:188419] E: DDC send command failed!
2021-02-19 21:04:35.279 ddcctl[3693:188419] E: VCP control #16 (0x10) = current: 0, max: 0

the request result i got was Request result = -536870206 (BadArgument error).
what changes did we need to get the correct brightness of the external monitor?

[kfix]

I don't have access to one of these monitors unfortunately.
That is an interesting error message (BadArgument)