related to this topic:

[if condition for MDI Parent Control](https://stackoverflow.com/questions/16475521/if-condition-for-mdi-parent-control/16475714?noredirect=1#16475714)

i need to call text from my label in *DtextEditoR* (form) to another label in *frmMain* (form) . and i use timer instead of button since i follow the answer here:
[Communicate between two windows forms in C#](https://stackoverflow.com/questions/1665533/communicate-between-two-windows-forms-in-c-sharp)

which leads to:

**frmMain.cs:**

```
private DtexteditoR a;
        public frmMain(Form callingForm)
        {
            a = callingForm as DtexteditoR;
            InitializeComponent();
        }

        private void timercountline_Tick(object sender, EventArgs e)
        {
                a.lblcl = lblcountline.Text;
        }

```

**DtexteditoR.cs**

```
public string lblcl //rich
        {
            get { return lblcountline.Text; }
            set { lblcountline.Text = value; }
        }

```

but the thing was this error always shows:
![enter image description here](https://i.stack.imgur.com/LM49G.png)

what should i do to remove that error? pls help thanks a lot!