Cannot delete rows more than one time

I am working on a shiny app. The server.R contains codes like:

dFt1 <- reactiveValues()
dFt1$dat <- data.frame(loadTransactionData())
...
output$t_tab_1 <- DT::renderDataTable({
    DT::datatable(
        dFt1$dat
        ,selection = list(mode = "single")
        ,options = list(
            rownames = TRUE
            ,pageLength = 10
            ,order = list(list(2,"desc"),list(1,"asc"))
        )
    )
})
...
observe({
    if (is.null(input$delete) || input$delete == 0){return()}
    session$sendCustomMessage(
        type = 'jsCode'
        ,list(value = 'confirm("Are You Sure?");')
    )
})

observeEvent(input$deleteConfirmChoice, {
    if (input$deleteConfirmChoice == "TRUE") {
        x <- input$t_tab_1_rows_selected
        deleteTransaction(x)
        isolate(dFt1$dat <- dFt1$dat[row.names(dFt1$dat) != x, ])
    }
})  

deleteTransaction <- function(x) {
    qy <- "DELETE FROM Transactions where timestamp = '<t>'"
    qy <- gsub("<t>",x,qy)
    db <- dbConnect(SQLite(), dbname=systemDatabase)
    dbGetQuery(db,qy)
    dbDisconnect(db)
}

And of course there is the delete button in the ui.R and a called to javascript confirm box.

The app runs good. I can select a record and delete it. Then I can select another record. But I cannot delete it. The javascript confirm box runs, but clicking Yes does not delete the record. I wonder why it is okay for one time but not the next time.

Here is another approach...

I changed the javascript code passed to session$sendCustomMessage. Clicking the No button returns 0. Clicking the Yes button returns a random number. This I hope will guarantee a different value in two consecutive clicks of the Yes button.

    observe({
    if (is.null(input$delete) || input$delete == 0){return()}
    session$sendCustomMessage(
        type = 'jsCode'
        ,list(value = 
            '
            (function() {
                if (confirm("Are you sure?")) {
                    return Math.random()*3 + 1;
                } else {
                    return 0;
                }
            })()
            '
        )
    )
})

observeEvent(input$deleteConfirmChoice, {
    if (input$deleteConfirmChoice == "TRUE") {
        x <- input$t_tab_1_rows_selected
        deleteTransaction(x)
        isolate(dFt1$dat <- dFt1$dat[row.names(dFt1$dat) != x, ])
    }
})  

Any other cleaner solution?