Run-time error '424' (object required)

Hello

The 424 error occurs when an object is necessary.
I’m having trouble to reference an instruction to a property of an object.
The object in question was created in a form and the instruction that needs it belongs to a class of functions.
I tried starting and restarting and create a new object in the function, but I got the error 91 (Object variable or with block variable not set).

Question: How do I refer the instruction to the object property already created?
Data: 1 -The instruction belongs to Excel.Application.
2- I’m using VB6