Your code is SQL injection vulnerable. Please read my past answer
] to get more details.
Your connection string is wrong:
Dim connectionString As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=FORM\FORM.xlsx;Extended Properties = ""Excel 12.0 Xml;HDR=YES"""
because the path to the file is incomplete! You have to provide full file name including full path.
Please, read notes provided here: Microsoft ACE OLEDB 12.0 Connection Strings - ConnectionStrings.com