Excel Vlookup only sometimes works

[Guest]

I am using VLookup on one tab to lookup data on another tab within the same spreadsheet. Some of the lookups work and some don't, even when I use the same values. As an example, I type 123 and get the correct answer. I try another cell and type 123 and get the right answer. Then I go back to the original cell and type 347 and get the right answer.

I have double checked the following.

1-The format of the cells in the table and lookup are identical.
2-The table is sorted
3-I've tried both True and False as the final parameter
4- The range $A$2:$B$129 is the same for all the cells I looking for

 

[Mark W.]

Make sure that the lookup value and table values are not just formatted alike, but also of the same data type.