Unable to get value from textbox??

hi,
I have a table in database called Newsletter.
NewsletterId - int
Date - datetime
address - nvar char
Optout - bool

From the aspx page in bootstrap  I just have  a textbox and Linkbutton -
in the event I try to get the value of textbox but
for some reason I am not able to get the value and
it goes into data table as null


      SUBSCRIBE TO OUR NEWSLETTER TO RECEIVE UPDATES  </label>&nbsp;&nbsp;                                                                           < ...