TextBox data validation or not empty

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VB

Dear All,

I using the under mention command to control on Zero/Blank Field at the time of storage of data.

CType(IIf(txttotal.Text = "", 0, txttotal.Text), String)

But is it possible that the cursor will not allow to move next on untill checking of data.

Else we have second option to done like that on each text

Private Function IsDataValid(ByVal InputData As String) As Boolean        'Return true if the input data is numeric.        
If Not IsNumeric(InputData) Then 
       ErrorProvider1.SetError(txtpatient_age, "Invalid age")            Label1.Visible = True        
Else            
Label1.Visible = False            
ErrorProvider1.Clear()          
End If   
End Function 

Major problem occurs when we have more than 25 Text box and want to valid date each of them.

[edit]Title - DON'T SHOUT! - OriginalGriff[/edit]