Board Game Arena

Greetings,
Would someone please explain to me why can't my Axis infantry on h4 & g4 can't attack Allies artillery on i2 or infantry on I1/ G1?
TIA

From page 8 of the rulebook:
"A unit adjacent to an enemy unit must Close Assault this unit if it chooses to battle. It may not fire on another, more distant, enemy unit instead."