i cant seem to get it to work

=IF(ISNUMBER(A1),A2,A1)

IF A1 is blank and there is a value in A2 i don't get anything

If A1 has a value and A2 has a value i get A2 which is right.

If A1 has a value but A2 does not, then again nothing

It seems that both A1 and A2 have to have numbers in their cells