=HVIS(Uge1!F4<>Rulleplan!D4;Uge1!F4;HVIS(ELLER(ER.TOM(Uge1!D4);ER.TOM(Uge1!E4));"";
HVIS(MINUTE(Uge1!D4)>0;TIME(Uge1!D4)&"."&MINUTE(Uge1!D4);TIME(Uge1!D4))&"-"&HVIS(MINUTE(Uge1!E4)>0;TIME(Uge1!E4)&"."&MINUTE(Uge1!E4);TIME(Uge1!E4))&" "&Uge1!F4))
or, in English

=IF(Uge1!F4<>Rulleplan!D4,Uge1!F4,IF(OR(ISBLANK(Uge1!D4),ISBLANK(Uge1!E4)),"",
IF(MINUTE(Uge1!D4)>0,HOUR(Uge1!D4)&"."&MINUTE(Uge1!D4),HOUR(Uge1!D4))&"-"&IF(MINUTE(Uge1!E4)>0,HOUR(Uge1!E4)&"."&MINUTE(Uge1!E4),HOUR(Uge1!E4))&" "&Uge1!F4))