First of all, the error is dead obvious:
objRs4.Open sql4, Conn
No place prior to that objRs4.Open line have you ever defined the variable Conn
But now we come to your next problem: Your query won't work.
You say your date is in the format dd/mm/yyyy.
Okay, consider these two dates, 60 days apart:
And now let's assume that the value in your database is
There is NO POSSIBLE WAY that '03' can be between '20' and '19'.
When you store dates AS STRINGS, the ONLY way you can then compare them is if you store them as yyyy/mm/dd.
Because STRINGS are compared ONE CHARACTER AT A TIME. And the first mismatch trigger the < or > result. In this case, the '0' of '03' is less than both the '2' or '20' and the '1' of '19' and so is NOT between them.
There MAY be hope for you:
What is the DATA TYPE of the field Cncrt_dateasp
in your table?
Use Access (the program, that is) to look at your table and examine that table deifinition and tell us the data type.