format Exception Error it appears when i try to send convert whats in TextBox1 in first form(into) : 
the program suppose to take +ve number from textbox1 in info form and send it to HR form to use it as array size(handled Error with try catch) but when i run the program it gives Error however i tried to send string then convert it in HR form instead of send it as shown in pic it gives Error in converting line

//first form(info)

`    
    HR frm=new HR(textBox1.Text);
     frm.show();
     this.close();`

//2nd form(HR)
`    static int size=0;
     public HR(string emplyee_num)
        {
             InitializeComponent();
            size =Convert.ToInt16(emplyee_num);//Error appear her instead
        }
`
 so how can i fix that Error and whats the reason

[Error in original code][1]


  [1]: https://i.stack.imgur.com/hUWWm.png