Dependent Data Valadiation

I'm having some Validation Issues.

Here is my Validation formula:

=IF(ISBLANK(B5),INDIRECT("entities"),INDIRECT(VLOOKUP(B4,acctlookup,
2,0)))

The Validation Lists works right; but it also is accepting anything
when I type directly into cell.

So first, I tried:

=entities (and that worked perfectly)

Then

=Indirect("entities") (and that worked perfectly)

but when I add the If statment, it starts allowing me to put anything
into the cell; but yet the dropdown list works as planned. It just
doesn't seem to validate anymore.

Any thoughts?

PS... I don't think we need to worry about 2nd part of the formula as
I don't think that is the problem. It just seems to be the "IF" thing
that is causing the problem. I say this because I change the if
formula to look like this:

=IF(ISBLANK(B5),INDIRECT("entities"),INDIRECT("accounts")) and still
go the error.