Microsoft Access Error

[ArthurCar]

Hi, I am the sole user of the program which I use to enter income/expenses for a small business. I have been using this database since the older versions of Access. Recently I have been getting this error "OpenForm action was canceled" when I click the Open Form button. Although I have been using the same button to open the "ENTRY" form (I have not changed the code in anyway), I am now getting the "OpenForm action was canceled". Here is the code.

Private Sub Command10_Click()
On Error GoTo Err_Command10_Click

Dim stDocName As String
Dim stLinkCriteria As String

stDocName = "ENTRY"
DoCmd.OpenForm stDocName, , , stLinkCriteria

Exit_Command10_Click:
Exit Sub

Err_Command10_Click:
MsgBox Err.Description
Resume Exit_Command10_Click

End Sub

I am not very knowledgeable in programming but I can understand some of the VBA codes and logic. Please help.