C# Error

[LostDream]

Hey, I'm using visual studio 2010 to code a C# program and it's thrown up this error

String was not recognized as a valid Boolean.

in relation to this code...

I can't figure out why, I've tried to error help but I can't make sense of it because I have two versions of the code and one words and the other doesn't.

The code is in relation to this code

if (theActivityBooking == null) //If new bookings are to be changed then display the below and change the below
                theActivityBooking = new ActivityHoliday(cmbWkOfHol.Text, txtName.Text, txtCusAddress.Text, [B] Convert.ToString(txtChildren.Text)[B], cmbActivityType.Text, Convert.ToBoolean(comboUnder16.Text));
            else
            {   //if editing an existing booking
                theActivityBooking.name = txtName.Text;
                theActivityBooking.week = cmbWkOfHol.Text;
                theActivityBooking.address = txtCusAddress.Text;
                theActivityBooking.children = Convert.ToString(txtChildren.Text);
                theActivityBooking.activitytype  = cmbActivityType.Text;
                theActivityBooking.CheckAge  = ageconvert(comboUnder16.Text);


            }

It's throwing up the error for this line in particular Convert.ToString(txtChildren.Text)

Thanks for any help you can provide