How to call a picture(BLOB) field from one table to another?

I need to capture digital signature of purchaser in PO printout. I have imported all signature in Salesperson/Purchaser table by using BLOB data type and a picture box. But it is not displaying in report of data item ‘Purchase Header’. All other fields like email, phone no are displaying except signature. And all the signatures are displaying in the report of dataitem Salesperson/Purchaser. Please advise on this.

Sorry to all. I have get the solution from my previous post solution suggested by John Popp . The problem was that I had forget to use CALCFIELDS function. Sorry for the inconvenience to all.