VLOOKUP Formula coming back with NA#

Hi,

I have created a template for my CRM, and want to creat a snapshot of each entry entered into one report. By doing this I have the user enter in the estimate number (quote reference number) and than all the details relating to it will be summarised in a report.

The formula I have used is
=IF(ISBLANK($D$6)," ",VLOOKUP($D$6,QuoteData,2,FALSE))

Isblank cell (D6) is the entry where you type in the quote number, this refers back to the main data sheet.

It is a simple request however, coming back as NA#, very frustrating.

I have attached an example for your viewing
The workbook is called Ziltek Opportunities register and the two worksheets in relationship to each other with the formula is - Quote Register and Opportunity Reprt

Please help
Thank you