Date formula not working 100% correct.

I am pulling data out of our application's charge master and want my Crystal Report to find the "most" recent assigned price and its' associated date see below:

If {PDRPROMAS_RECORD.PF_PRICE10_00001}>0 and not ISNULL ({PDRPROMAS_RECORD.PF_PRICE9_DT_00001}) then
({PDRPROMAS_RECORD.PF_PRICE9_DT_00001}) else if

{PDRPROMAS_RECORD.PF_PRICE9_00001}>0 and not ISNULL ({PDRPROMAS_RECORD.PF_PRICE8_DT_00001}) then
({PDRPROMAS_RECORD.PF_PRICE8_DT_00001}) else if

{PDRPROMAS_RECORD.PF_PRICE8_00001}>0 and not ISNULL ({PDRPROMAS_RECORD.PF_PRICE7_DT_00001}) then ({PDRPROMAS_RECORD.PF_PRICE7_DT_00001}) else if

{PDRPROMAS_RECORD.PF_PRICE7_00001}>0 and not ISNULL ({PDRPROMAS_RECORD.PF_PRICE6_DT_00001}) then
({PDRPROMAS_RECORD.PF_PRICE6_DT_00001}) else if

{PDRPROMAS_RECORD.PF_PRICE6_00001}>0 and not ISNULL ({PDRPROMAS_RECORD.PF_PRICE5_DT_00001}) then
({PDRPROMAS_RECORD.PF_PRICE5_DT_00001}) else if

{PDRPROMAS_RECORD.PF_PRICE5_00001}>0 and not ISNULL ({PDRPROMAS_RECORD.PF_PRICE4_DT_00001}) then
({PDRPROMAS_RECORD.PF_PRICE4_DT_00001}) else if

{PDRPROMAS_RECORD.PF_PRICE4_00001}>0 and not ISNULL ({PDRPROMAS_RECORD.PF_PRICE3_DT_00001}) then
({PDRPROMAS_RECORD.PF_PRICE3_DT_00001}) else if

{PDRPROMAS_RECORD.PF_PRICE3_00001}>0 and not ISNULL ({PDRPROMAS_RECORD.PF_PRICE2_DT_00001}) then
({PDRPROMAS_RECORD.PF_PRICE2_DT_00001}) else if

{PDRPROMAS_RECORD.PF_PRICE2_00001}>0 and not ISNULL ({PDRPROMAS_RECORD.PF_PRICE1_DT_00001}) then
({PDRPROMAS_RECORD.PF_PRICE1_DT_00001})

My issue is the correct price data is being pulled however, in "some" instances my price date field is blank (see attached).

Using the application's internal report writer I was able to pull procedure 3290001 and and all of the associated  prices with the price of $122.00 displaying however, the most recent price date is not displayed.(?) 

Likewise, 3290002 should also be displaying a date field.

Thanks