I have a dropdown list.If no selection is made, the system saves a null value in

I have a dropdown list.If no selection is made, the system saves a null value into the component's Save Selection To field.Confused by this Error - "A dropdown component [label=“Company”] has an invalid value for “value”. All selected values must be present in the choiceValues array, but value was and choiceValues was ABI2WG ; ACC1LON ; ACEI4BRI; ACI2SYD ; ".
Expression Error : "Expression evaluation error in rule 'vc_mc_brokercontactdetail' (called by rule 'vc_mc_managecontacts'): A null parameter has been passed."
Below is the code which renders it
a!dropdownField(
label: cons!VC_LB_COMPANY,
labelPosition: cons!VC_LB_POSITION_ADJACENT,

choiceLabels: {
apply(fn!tostring,local!brokerCompany.id)
},
choiceValues: {
apply(fn!tostring,local!brokerCompany.id)
},
placeholderLabel: cons!VC_CMS_LB_PLACEHOLDER_SELECT...

OriginalPostID-150440

OriginalPostID-150440