Develop a formula for putting into table in a Libreoffice Writer document

Small task: I need a solution for D2. Currently the formula is: B2 * C2. If there is no value in B2 or C2, there is still value 0,00 appearing. I need a new formula: If B2 or C2 is empty, then D2 must also be empty. If there is B2 and C2 given, then the value B2 * C2 should appear. It tried with IF(ISBLANK) but I wasn't successful: **expression is faulty**