Vlookup & addition

Happy Christmas and New Year,

I'm hoping someone more intelligent than myself can get out of a bind. I have multiple ranges in a spread sheet. I am trying to write a formula that will go out to each range in succession and look for a part number, upon finding return a quantity and them move on to the next range duplicating the above process. The formula should tally the grand total of all numbers found. I have it working except that not all of my items are in all ranges. If the item that I am searching for is in all ranges my formula works but if there is one or more of the ranges that doesn't have that particular value it returns an #n/a instead of totalling those that do have it. If I use a true instead of false in my [range_lookup] I get an incorrect answer. My formula for a given cell is listed below. This is with the true argument which does not work.

=SUM(VLOOKUP($A135,$P$104:$S$170,4,TRUE)+VLOOKUP($A135,$T$104:$W$170,4,TRUE)+VLOOKUP($A135,$X$104:$AA$170,4,TRUE)+VLOOKUP($A135,$AB$104:$AE$170,4,TRUE)+VLOOKUP($A135,$AF$104:$AI202,4,TRUE)+VLOOKUP($A135,$AJ$104:$AM$170,4,TRUE)+VLOOKUP($A135,$AN$104:$AQ$170,4,TRUE)+VLOOKUP($A135,$AR$104:$AU$170,4,TRUE)+VLOOKUP($A135,$AV$104:$AY$170,4,TRUE)+VLOOKUP($A135,$AZ$104:$BC$170,4,TRUE)+VLOOKUP($A135,$BD$104:$BG$170,4,TRUE)+VLOOKUP($A135,$BH$104:$BK$170,4,TRUE)+VLOOKUP($A135,$BL$104:$BO$170,4,TRUE)+VLOOKUP($A135,$BP$104:$BS$170,4,TRUE)+VLOOKUP($A135,$BT$104:$BW$170,4,TRUE)+VLOOKUP($A135,$BX$104:$CA$170,4,TRUE)+VLOOKUP($A135,$CB$104:$CE$170,4,TRUE)+VLOOKUP($A135,$CF$104:$CI$170,4,TRUE))