I have created an IF statement which I use to search a string for the letter
"a", and "a" can appear multiple times in the string. A value of "1" is
assinged each time "a" is found. I would like to know the SUM of values for
"a".

My IF statement is:
IF(ISERR(IF(SEARCH("a",$B2)0,1,0)),0,IF(SEARCH("a ",B2)0,1,0)).

I would like to include this condition in the above IF Statement.
IF B20,SUM(B2),0)