Preventing duplicate entries of username - duplicates

Question

Private Sub APMSubmitBTN_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles APMSubmitBTN.Click
con = New OleDbConnection(cs)
con.Open()
If txt_appmngr_username.Text = "" Then
MessageBox.Show("Please enter Employee Name", "Input Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
txt_appmngr_username.Focus()
Exit Sub
End If
If txt_appmngr_password.Text = "" Then
MessageBox.Show("Please enter password", "Input Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
txt_appmngr_password.Focus()
Exit Sub
End If
If chck_box_admin.Checked Then
Dim sqlCheck As New OleDbCommand
Dim cb As String = "INSERT INTO Admin_Account([Admin_User],[Admin_Pass]) values (#a1,#a2)"
cmd = New OleDbCommand(cb, con)
'CHECKING WETHER THE USERNAME IS ALREADY TAKEN BY OTHER ADMINISTRATOR'
sqlCheck.CommandText = "SELECT count(*) FROM Admin_Account WHERE Admin_User = #1"
sqlCheck.Connection = con
cmd.Parameters.AddWithValue("#a1", txt_appmngr_username.Text)
Dim oleRdr As OleDbDataReader = sqlCheck.ExecuteReader
If oleRdr.HasRows = True Then
oleRdr.Read()
If oleRdr.Item(0) = 0 Then
MessageBox.Show("Username is available", "Registration", MessageBoxButtons.OK, MessageBoxIcon.Information)
Else
MessageBox.Show("Username is unavailable", "Registration", MessageBoxButtons.OK, MessageBoxIcon.Error)
End If
End If
cmd.Parameters.AddWithValue("#a2", txt_appmngr_password.Text)
cmd.ExecuteReader()
MessageBox.Show("Successfully registered as Admin", "Registration", MessageBoxButtons.OK, MessageBoxIcon.Information)
con.Close()
ElseIf chck_box_user.Checked Then
Dim sqlCheck As New OleDbCommand
Dim cb As String = "INSERT INTO Staff_Account([Staff_User],[Staff_Pass]) values (#s1,#s2)"
cmd = New OleDbCommand(cb, con)
'CHECKING WETHER THE USERNAME IS ALREADY TAKEN BY OTHER STAFF'
sqlCheck.CommandText = "SELECT count(*) FROM Staff_Account WHERE Staff_User = #s1"
sqlCheck.Connection = con
cmd.Parameters.AddWithValue("#s1", txt_appmngr_username.Text)
Dim oleRdr1 As OleDbDataReader = sqlCheck.ExecuteReader
If oleRdr1.HasRows = True Then
oleRdr1.Read()
If oleRdr1.Item(0) = 0 Then
MessageBox.Show("Username is available", "Registration", MessageBoxButtons.OK, MessageBoxIcon.Information)
Else
MessageBox.Show("Username is unavailable", "Registration", MessageBoxButtons.OK, MessageBoxIcon.Error)
End If
End If
cmd.Parameters.AddWithValue("#s2", txt_appmngr_password.Text)
cmd.ExecuteReader()
MessageBox.Show("Successfully registered as Staff", "Registration", MessageBoxButtons.OK, MessageBoxIcon.Information)
con.Close()
End If
End Sub
Im getting error on the line of Dim oleRdr As OleDbDataReader = sqlCheck.ExecuteReader of both 'user and admin accounts. when i run a program.
The error said "No value given for one or more required parameters."