So you say you have a table (pdfFolder) like,
ID |    folderPath
---+------------
1  |    C:\Temp\
2  |    D:\Test\
3  |    E:\Sales\
With your DLookup, the value in varFolder should be "D:\Temp\".
If the answer is 'Yes', then what is your problem? If the answer is 'No', what is your problem?