VLOOKUP Function *is not* broken in LO for Windows

just for the record: VLOOKUP IS NOT BROKEN BUT YOUR SOURCE-DATA (edit by karolus)

I use multiple VLOOKUP functions to select and to consolidate data. The Workbook was created in LO version for Windows and was working fine on a Windows 7 laptop. Then I copied the Book to a desktop computer running Windows 7 with a fresh install of LO and opened the file. Many of the VLOOKUP functions no longer worked correctly. When searching a Table where the index field is sorted but has duplicates some lookups worked correctly, some returned the result from the LAST row containing that index value and some returned N/A. Changing the index value on the destination page from numerical 1,2,3,4 etc to text 1,2,3,4 etc fixed some and broke others. Then I found the results of the VLOOKUP changed from the first row with a particular index value to the last row with that index value when I included the VLOOKUP inside an IF statement.

Please can you attach a minimal sample file. (Voted the question, so you can upload the sample).

OK. I see from other questions on VLOOKUP that the size of the sheets may make a difference too so I am not sure how large a minimal sample might need to be. The whole file is 660 KB. I will take a copy and remove personal data and have a go at uploading. Laurie.
Further: The two sheet 38 KB sample I made worked perfectly in both versions. The differences:- (1) File size. (2) source sheet all text values except the index column.
The misbehaving source sheet is the result of multiple VLOOKUPs.

The problem appears to have been that LO 4.4 is more fussy about data inconsistencies than LO 4.0. On the Primary Source Sheet Sheet, one group of account numbers were stored as numbers and another as Text. HLOOKUPS and VLOOKUPs select a month/column into a Summary/Calculate Sheet which works out charges. The misbehaving VLOOKUP assembles the non-zero charges onto another Sheet. Changing all of the account numbers to be text fixed it AND the strange IF statement behaviour disappeared. (Later) When more data added VLOOKUPS do not complete. Editing the iterations in Calculate up or down fixes it; for that session only. Same file still OK in 4.0 even with iterations=2.