Array fundamentals

Hi all,
I got 2 complementary functions, which will do opposite things.
1 - CombineStrings(stringarray character varying[])  RETURNS character varying
This one will take as parameter an array of strings and will return a string with some formatted information inside
2-  SplitString2Array(stringtosplit character varying)  RETURNS character varying[] 
This one will take as parameter a formatted string and will return an array of string

The following is true, both works just fine : 
select SplitString2Array(CombineStrings(ARRAY['abba', 'queen']))
will return {'abba', 'queen'}

Now, if I want do do the following:
select CombineStrings(ARRAY[SplitString2Array("SomeTextColumn"), 'New string to add']) from "SomeTable"

i get the following error:
array value must start with "{" or dimension information

What am I doing wrong, I am feeling I still don't get the array fundamentals. My goal is to add to inside formatted information in the column "SomeTextColumn" my new string 'New string to add' in the same manner if I would been used the following:
Insert into "SomeTable"("SomeTextColumn") values (CombineString(ARRAY['abba', 'queen', 'New string to add']))

Thank you in advance,
Danny