Invalid Use of Null (IF..THEN)

[BigC666]

Here is my code...

Private Sub Authorize_Click()
On Error GoTo Err_Authorize_Click

Dim Field As String
Dim Check As Boolean

Field = Me!AuthorizationNumber
Check = IsNull(Field)

If (Check = True) Then
Randomize
Me!AuthorizationNumber = Int(RND * 1000000000)
Else
MsgBox "This Ticket Has Already Been Authorized"
GoTo Exit_Authorize_Click

End If

Exit_Authorize_Click:
Exit Sub

Err_Authorize_Click:
MsgBox Err.Description
Resume Exit_Authorize_Click

End Sub

If there is a value in the AuthorizationNumber Field then the msgbox displays if there is no value I get The Invalid Use of Null Error. What am I doing wrong? Any help would be greatly appreciated.

 

[BVerlaan]

In your Sub you try to evaluate the variable Field of type String. As far as I know a String cannot become a Null.
A control, like Me!AuthorizationNumber can.

Try:
Dim Check As Boolean

Check = IsNull(Me!AuthorizationNumber)

The function IsNull returns a true or a false. True if the variable o be evaluated is a Null, false if the variable to be evaluated in not a Null.

Think it will do the job.

Good luck, Bart V.

 

[BigC666]

Private Sub Authorize_Click()
On Error GoTo Err_Authorize_Click




Field = Me!AuthorizationNumber
Field1 = Me!TicketID

If IsNull(Field) = True And IsNull(Field1) = False Then
Randomize
Me!AuthorizationNumber = Int(RND * 1000000000)
Else
MsgBox "This Ticket Has Already Been Authorized"
GoTo Exit_Authorize_Click

End If

Exit_Authorize_Click:
Exit Sub

Err_Authorize_Click:
MsgBox Err.Description
Resume Exit_Authorize_Click

End Sub

This is what I used to get it to work. Any other tips will be welcomed with open arms. Thank you for your help!