I'm getting a feeling of deja vu ... i.e. we've been through this before.
In the debugger put a breakpoint on the line
int iTextBoxFTE40 = Convert.ToInt32(TextBoxFTE40.Text);
and then start stepping through the code (usually F10/F11) and observe what happens.
First
iTextBoxFTE40
is
not less than 40 (Assuming TextBox1 is actually TextBoxFTE40) so processing will move on to the next
if
statement.
It's not greater than 140 either, so processing will move on to the next
if
statement...
Now assuming TextBox2 is
TextBoxHC50
then it is equal to 50, which is not greater than 150, so ... processing moves on to the next
if
statement.
Finally assuming TextBox3 is TextBoxFTE4050 and equals 90, it is not greater than 290 so processing moves out of this code block all together....
without anything actually being assigned or actioned and that is why nothing changes each time this is run.
There are ways to clean this up but mainly you need rethink your overall logic.