I have been building a webpart that needs client side validation. I kept getting the error:
"Unable to find control id txtNotes referenced by the 'ControlToValidate' property"
Now most of the posts say just use the command to get the 'real' ID at runtime
this.rfvNotes.ControlToValidate = this.txtNotes.ClientID;
But this did not work, in the end the form I found worked was:
protected override void OnInit(EventArgs e)
this.txtNotes.ID = "txtNotes";
this.rfvNotes.ControlToValidate = this.txtNotes.ID;
this.rfvNotes.Enabled = true;
this.rfvNotes.Text = "* Required";
The key step was to set the textbox ID manually, it seems that if this is not done it is the root of the error.