Can someone please help me get this to compile

Is the error message the same?

Now you have a new error in that you are starting with an else if instead of just and if.

Then the secondary if is not in the always block. (because no else condition on the reset)

Things to try: Add more () to the code:

double check begin end and if/else statements.

try making it a sync reset block by removing the "or negedge RST" from the sensitivity list. (Although this shouldn't be the issue) with the async reset as the first statement.

Try using bitwise and versus logical and "&" instead of "&&" in the if statement.

use more () to insure no order of operation issue is the cause of your grief..

IE

if ((SIGNAL_IN==4'b0100) & (A_reg== 4'b0010))