Randbetween Range Problem

[SBrooky]

Hello,
Im using randbetween to get a random number from a list on a different sheet but the list is between F2 and F521 but it can contain blanks. It is always sorted to the top so is there a way to make it look for a value from F2 to the last cell with a value then stop.

My rand at the moment:

=RANDBETWEEN(Sheet1!F2,Sheet1!F521)

the list in F2 is basically a list of this:

=IF(ISERROR(SMALL($B$2:$B$521,ROW()-1)),"",SMALL($B$2:$B$521,ROW()-1))

Which is in cells F2 to F521 but sometimes only the top 5 cells (F2,F3,F4,F5,F6) might have values or top 290 whatever.

Not sure how clear I am here, If you want me to upload a sample ill do it.

Any help would be great!