getting wrong results with my VLOOKUP usage

[NoviceUser]

The Situation: am using two worksheets, prices05 (largest number of records)
and cat05 (smaller subset of number of records found in prices05)

Goal: need to get data from worksheet prices05, col B into cat05, col B.
Currently am using this formula:
=VLOOKUP('prices05'!A2,'prices05'!A2:B2,2,FALSE)

This formula works only until row 4 in prices05 (see below). That's because
there's an additional record in prices05 that's not found in cat05. At that
point everything gets shifted down. This happens repeatedly.

Is VLOOKUP the wrong way to go? What is the answer. If using the match and
index funtions or some type of conditional statement better, please advise.
And be real clear.

Urgent. Any assistance greatly appreciated. T h a n k y o u.

prices05 (original, first worksheet)
(col A) (col B)
1 catNumber 05prices
2 125-0001 111
3 125-0002 500
4 125-0176 347
5 125-0233 800

cat05 (new, second worksheet)
(col A) (colB)
1 catNumber prices
2 125-0001 (works, get correct price: 111)
3 125-0002 (works, get correct price: 500)
4 125-0233 (wrong price: 347)

NoviceUser
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510-741-6496