"Enter Parameter Value" dialog box appears when I run my query

"Enter Parameter Value" dialog box appears when I run my query

I have a form that contains two text boxes to search for a first name and
a last name and a button to run the query. However, when the button is
clicked, the enter parameter value dialog box appears for each text feild.
Also, I have another textbox and button to search for positions, same
thing happens. I created a test database and form at home in access 2007
using the same code (using 2010 at work), and the dialog box doesn't
appear. I'm pretty new to access, so it's possible I'm overlooking
something. But, I'm clueless to as what it is. I've search here and google
for a solution, but nothing has worked. Any help is greatly appreciated.
SELECT dbo_Apptable.AppID, dbo_Apptable.Date, dbo_Apptable.Position,
dbo_Apptable.Referral, dbo_Apptable.LastName, dbo_Apptable.FirstName
FROM dbo_Apptable
WHERE (((dbo_Apptable.LastName) Like "*" & Forms![Main Menu]![Last Name] &
"*") And ((dbo_Apptable.FirstName) Like "*" & Forms![Main Menu]![First
Name] & "*"));
SELECT dbo_Apptable.AppID, dbo_Apptable.Date, dbo_Apptable.Position,
dbo_Apptable.Referral, dbo_Apptable.LastName, dbo_Apptable.FirstName
FROM dbo_Apptable
WHERE (((dbo_Apptable.Position) Like "*" & [Forms]![Main Menu]![Position]
& "*"));