KL and Sandy Man helped with my first problem, time for my second

A b c d e
120873 50183368 6 blank REL NMAT PRC SETC
120873 50183299 4 blank CLSD PRT NMAT PRC
122873 50185108 3 blank PCNF NMAT PRC SETC
122873 50178522 3 HUDS002277 TECO PCNF PRT NMAT
122873 50147658 5 HUDS003115 REL NMAT PRC SETC

I want to count only those records in column C with a 3 in and where a blank
(null) exists in column D. I have pieced togther the following based on
previous help, but doesn't work. I want the range to equal the contents of a
column because the data will vary on a month by month basis and I want people
to simple paste their data into a sheet and it calculates everthing on a
separate sheet.

=SUMPRODUCT(--(Sheet1!C1="1"),--(LEFT(Sheet1!D1,3)<"HUD*"))
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Regards vipa