I have a relatively simple table which I want to use with a VLOOKUP Formula
(or similar). In column C, articles (text) will be entered from a table that
goes from column X4 to Z50; columns Y and Z contain the two prices in the
same line as the article (text) in col. X. Column C is indefinitely long.

Therefore, I tried to use the formula =IF(C4=0,0,VLOOKUP(C:C,$X$4:$Z$50,2))
and/or =IF(C4="","",VLOOKUP(C:C,$X$4:$Z$50,3)) respectively to retrieve the
prices in 2 columns (H and K). The list in column X is sorted alphabetically.
The entries in columns C should, however, be in any order as they are entered
one by one. (With validation to the list in X to avoid misspelling)

The formulae work well in the first eleven lines, but when I copy them
further down, only articles down to X27 get prices, those from X28 down do
not! What do I do wrong? Or is it maybe another formula?