You need insert value into database use textbox text,
first you verified database table value fields datatype(int or float or char)
[osi_no] [int] IDENTITY(1,1) NOT NULL
, this is datatype is int.
so you could not insert textbox text because text for datatype is string,
so you convert to implicit or explicit.
example
+ int.Parse(txtOSITDSFromBank.Text)
or
converto.Int32(txtOSITDSFromBank.Text)