How to find a difference between time and prompting a message in case of a blank cell

Here I need to try to find the difference between the created date and the initial approval. I've tried the following formula

=IFERROR(IF(IF(AND(ISBLANK(B3),ISBLANK(C3)),"Enter dates"), IF(ISBLANK(B3),"Enter Created date"),IF(ISBLANK(C3),"Enter Initial Approval date",IF(C3<B3,"Enter correct date",C3-B3))),"Dates are Missing")

When the created date cell is blank, the formula is not prompting the error message.

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Can anyone please help me?