I have 2 workseets - A and B

Spreadsheet A and B have columns (column C and column A, respectively) with
similar values.

The formula in column D of spreadsheet A has formula:
=if(iserror(VLOOKUP(C2, B!$A$1:$B$100,2,FALSE)),"Not Available",VLOOKUP(C2,
B!$A$1:$B$100,2,FALSE))

Spreadsheet B has a table with 2 columns - column A has values similar to
column A!C, column B has target values.

Column A!D shows #N/A, even though values in A!C and B!A match!
I sorted B!A1:B100 out, I made it General type, and I manually tracked
several values, they should be looked up by the formula, but A!D still shows
#N/A!!

Anybody can help ? Thanks!