VBA Program works some times and some times gives me a Run-time error '1004'?

I have a simple excel spread sheet that uses VBA to add and delete a list of products. Some times it works without an error and some times it crashes with error 1004.
It says Method 'Range' of object_'Worksheet' failed. The problem occurs when I try to call my User Form, which is invoked by a button on my workbook LagTime

Sub EditProduct()
    
    frmEditProduct.Show False
    
End Sub

Any suggestions on what I have done wrong? Thanks, redsab