session value lost

Hello NG,

I have three files (default.aspx, search.aspx and work.aspx). The way
is: login on default (if session is newsession). The loginname I write
into as sessionvariable (username). So I redirect to my search.aspx.
Here I have a form which allows fill in some fields (place, street,
name etc.). With this informations i build a sqlquerey for sqlserver,
fill a datagrid and after select the right record by usin a link behind
I save the recordid to the session and redirect to work.aspx. With a
new sqlstring I fetch the data from the sqlserver. But this data is
only to display. The user can edit Data for a new record in anoter
table and end it wiht button click. Here I will save all sessionvalues
(username, and recordinformation) with sqlstring and redirect to
search.aspx.

Now the problems:
1. I don't no what I've changed - but I have to...
After redirection from work to search I've got an sql-error. The string
will be cleard before building new, so why does it run once, but not
after redirect?
2. I solved this problem with redirecting from work to default. Its
running. But: the session username is empty - why?
3. I solved with writing the username in an hidden field on
default.aspx, read it again and write to session. Everything is fine.
4. Now we can work, and I will change the username from manuel login to
reading from client windows. But I realy want to know why I have the
Problems 1 to 3 and problem no 4 is: some stored records have no
username within. Who can explain it to me - who as a solution to solve
the problems?

.