Weird Workflow Behavior in Sharepoint 2007

I have a Document Library A and a list B.

When a document added to A, an item is created in B with the Title = A.Url. Another workflow runs whenever a document is updated in A which makes a lookup: B.Title = A.Url, and changes another column in B in found item.

Item Change Workflow always gives "Error Occurred: List item is not found". I modified the workflow to send me an e-mail containing the new (but unchanged) A.Url. It sent me the exact string with the one already in list B.

Anyways, why it can't find the item when the two columns are equal?

Thanks in advance.

Edit:

I literally hate Microsoft Sharepoint.

This is going to seem very unintuitive, but try "Building a Dynamic String" into a String variable, containing only [URL] from list A (or whatever the field name is). Then use this variable to perform your lookup against list B.

This voodoo magic has often worked for me when I encounter string comparison mysteries in SPD workflows.