Javascript Calculation Not Working

My java script calculation not working, please can you hellp me. See below the code and the html markup.

<script>

    function CalcFxedExpenses() {
        let RemExp = document.getElementById("RemuneratnExp1").value;
        let RentExp = document.getElementById("RentalExp1").value;
        let InsurExp = document.getElementById("InsuranceExp1").value;
        let TaxesExp = document.getElementById("TaxExp1").value;
        let InterExp = document.getElementById("InterestExp1").value;
        let PrincDebtExp = document.getElementById("PrincipalDebt1").value;
        let DeprExp = document.getElementById("DepreciatnExp1").value;
        let BankChrgExp = document.getElementById("BankCharges1").value;
        let AdvertExp = document.getElementById("AdvertisingExp1").value;
        let OthFxExp = document.getElementById("OtherFxdExp1").value;
        let TotalFxdExpen = (RemExp + RentExp + InsurExp + TaxesExp + InterExp + PrincDebtExp + DeprExp + BankChrgExp + AdvertExp + OthFxExp);
        document.getElementById("TotalFixedExp1").value = TotalFxdExpen.toFixed(2);
        return false;
    }

</script>

<div class="row">
    <div class="col-md-4">
        <form asp-action="WorkBreakEven">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <div class="form-group">
                <label asp-for="WrkDocNumb" class="control-label"></label>
                <input asp-for="WrkDocNumb" class="form-control" />
                <span asp-validation-for="WrkDocNumb" class="text-danger"></span>
            </div>
            <a asp-controller="WorkNumberings" asp-action="WorkNumbering">Check how to create a number</a>
            <div class="form-group">
                <label asp-for="CurrntDate" class="control-label"></label>
                <input asp-for="CurrntDate" class="form-control" />
                <span asp-validation-for="CurrntDate" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="RemuneratnExp" class="control-label"></label>
                <input asp-for="RemuneratnExp" class="form-control" id="RemuneratnExp1" />
                <span asp-validation-for="RemuneratnExp" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="RentalExp" class="control-label"></label>
                <input asp-for="RentalExp" class="form-control" id="RentalExp1" />
                <span asp-validation-for="RentalExp" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="InsuranceExp" class="control-label"></label>
                <input asp-for="InsuranceExp" class="form-control" id="InsuranceExp1" />
                <span asp-validation-for="InsuranceExp" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="TaxExp" class="control-label"></label>
                <input asp-for="TaxExp" class="form-control" id="TaxExp1" />
                <span asp-validation-for="TaxExp" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="InterestExp" class="control-label"></label>
                <input asp-for="InterestExp" class="form-control" id="InterestExp1" />
                <span asp-validation-for="InterestExp" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="PrincipalDebt" class="control-label"></label>
                <input asp-for="PrincipalDebt" class="form-control" id="PrincipalDebt1" />
                <span asp-validation-for="PrincipalDebt" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="DepreciatnExp" class="control-label"></label>
                <input asp-for="DepreciatnExp" class="form-control" id="DepreciatnExp1" />
                <span asp-validation-for="DepreciatnExp" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="BankCharges" class="control-label"></label>
                <input asp-for="BankCharges" class="form-control" id="BankCharges1" />
                <span asp-validation-for="BankCharges" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="AdvertisingExp" class="control-label"></label>
                <input asp-for="AdvertisingExp" class="form-control" id="AdvertisingExp1" />
                <span asp-validation-for="AdvertisingExp" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="OtherFxdExp" class="control-label"></label>
                <input asp-for="OtherFxdExp" class="form-control" id="OtherFxdExp1" />
                <span asp-validation-for="OtherFxdExp" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="TotalFixedExp" class="control-label"></label>
                <input asp-for="TotalFixedExp" class="form-control" id="TotalFixedExp1" />
                <span asp-validation-for="TotalFixedExp" class="text-danger"></span>
            </div>
            <br />
            <input type="submit" value="Calculate Fixed Expenses" class="btn btn-primary" onclick="return CalcFxedExpenses()" />