Get text in a textbox

Good morning every body! Please help me out in this since I can't really figure out what is wrong.
I have a datalist control that displays posted status. Inside this datalist is a textbox control and a button 'Add idea'. I want visitors to add their own idea so I used this code

PublicSub AddIdea(ByVal sender AsObject, e As DataListEventsCommand...)
Dim txt As TextBox = e.Item.FindControl("txtidea")
If txt.Text <> ""Then
MsgBox (txt.Text)
Else
MsgBox ("No idea entered")
EndSub

But if the Add idea button is heat, the msgbox returns an empty string. Help please.