Conditional Else Statwment does not work

am trying to add a simple conditional statement in my archive page in order to display some categories different from the rest.

The if (is (is_cat)) part runs ok but as soon as I choose a category which is not part of the if(cat) and therefore relies on the ‘else’ part I get a blank white screen …everytime

I have stared at the code and looked arounf for a reason as to wha it does ot work but I cannot see the error ..anyone else, please??

and if anyone knows of a resource which details using conditional tags in loops – I am tired of only finding posts on the most basic examples – could they please add that too …thanks

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