you can customized these parameters (They are in the parent ValidationTextBox of FilteringSelect):
// required: Boolean
// User is required to enter data into this field.
required: false,
// promptMessage: String
// If defined, display this hint string immediately on focus to the textbox, if empty.
// Also displays if the textbox value is Incomplete (not yet valid but will be with additional input).
// Think of this like a tooltip that tells the user what to do, not an error message
// that tells the user what they've done wrong.
//
// Message disappears when user starts typing.
promptMessage: "",
// invalidMessage: String
// The message to display if value is invalid.
// The translated string value is read from the message file by default.
// Set to "" to use the promptMessage instead.
invalidMessage: "$_unset_$",
// missingMessage: String
// The message to display if value is empty and the field is required.
// The translated string value is read from the message file by default.
// Set to "" to use the invalidMessage instead.
missingMessage: "$_unset_$",
// message: String
// Currently error/prompt message.
// When using the default tooltip implementation, this will only be
// displayed when the field is focused.
message: "",
If you set required to false, it should not prompt message, can you post you code.