Excel Previous Month & Latest Balance

Hello
I am doing this chart in a Big database & sort it in Short table for each understanding.

The example show's of July transaction
June no transaction of this company.
Need the LAST balance of
June 30 and
July 31

Need formula of last month balance and present month balance.

in my file & am using this formula
=LOOKUP(2,1/(TEXT($A$3:$A$300,"mmyy")=TEXT(B820,"mmyy")),$J$3:$J$300)
but result shows #n/a
if the table i mention june 30 = 29,000
then the result shows correct = 29,000

in my table
B820 = a date that is 6/30
J is Amount
A is Date


Please update