I have now copy/pasted around 5 different examples of cascading combo boxes, and no matter how I try, the second box just turns up blank. I have gone through step by step tutorials several times, and nothing works. I noticed when downloading a sample database, that the combo boxes on the forms were unbound. Is this perhaps a requirement?

I am a total beginner with Access. My tables are set up as follows:

tblCategories:
ID                AutoNumber   (PK)
CategoryName      Text

tblSubCategories:
ID                AutoNumber   (PK)
SubCategoryName   Text
Category          Number       (FK)

Both category and subcategory are foreign keys in my tblInventory table, over which I want a form in which the subcategory combo box is filtered by the category combo box. I have tries all manners of VBA to update the rowsource of cboSubcategory on the After_Update event of cboCategory.

Is there some fundamental flaw to my approach, or do you think I have simply misunderstood some crucial step in the process?

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Answer from Richard Rost:

Here is how I handle cascading combo boxes:

I get asked this question all the time. You've got two or more combo boxes and you want the first one to filter the second one. I get asked this so much that I recorded a video tutorial explaining how to do it:

http://599cd.com/tips/access/two-combo-boxes?key=BlFAlEx