Coalesce and trim function

Question

I am trying to execute the below script

CREATE VIEW JOES.WEBSKULOOKUPVIEW ( 
    STYLEID , 
    STYLENAME , 
    DISPLAYSTYLENUMBER , 
    B2BSTYLE , 
    WEBPRODDESCR , 
    WEBSTYLENAME , 
    WEBSKUNUMBER , 
    SUPPLIERNAME , 
    SKUID , 
    SKUNUMBER , 
    SKUACTIVESTATUS , 
    B2BSKU , 
    SKUSIZE , 
    SKUCOLOUR , 
    WPSTYLEID ) 
    AS 
    SELECT DISTINCT ESTYLE.STYLEID, ESTYLE.STYLENAME, ESTYLE.DISPLAYSTYLENBR, ESTYLE.B2BSTYLE, WPROD.H1SJXT, WPSTYLE.H2AMNA, 
                    WPSKU.H3DINB, SUPP.SUPPLIERNAME, ESKU.SKUID, ESKU.SKUNUMBER, ESKU.SKUACTIVESTATUS, ESKU.B2BSKU,  
                    (COALESCE(TRIM(FIRSTSIZE.SHORTSCALEVALUE) , '') || COALESCE(TRIM(', ' || SECSIZE.SHORTSCALEVALUE), '')) AS "SIZE",  
                    STYLEACTUALCOLOUR.SPECIFICCOLOURNAME , STYLE.STYLEID  
                    FROM ENTERPRISE.STYLE ESTYLE, ENTERPRISE.SUPPLIER SUPP, MWWDATA.DGH1CPP WPROD,  
                     MWWDATA.DGH2CPP WPSTYLE, MWWDATA.DGH3CPP WPSKU, ENTERPRISE.STOCKKEEPINGUNIT ESKU, ENTERPRISE.STYLEACTUALCOLOUR STYLEACTUALCOLOUR,  
                     ENTERPRISE.STYLE STYLE, ENTERPRISE.STYLEACTSTATUS STYLEACTSTATUS, ENTERPRISE.STYLEACTSTATUS SKUACTSTATUS, ENTERPRISE.SKUSIZE SKUSIZE  
                    LEFT OUTER JOIN ENTERPRISE.SIZESCALEVALUE FIRSTSIZE ON FIRSTSIZESCALEID = FIRSTSIZE.SIZESCALEID AND FIRSTSIZESCALEOBJI = FIRSTSIZE.SIZESCALEOBJID  
                    LEFT OUTER JOIN ENTERPRISE.SIZESCALEVALUE SECSIZE ON SECSIZESCALEID = SECSIZE.SIZESCALEID AND SECSIZESCALEOBJID = SECSIZE.SIZESCALEOBJID          
                    WHERE   ESTYLE.DEFAULTSUPPLIERID = SUPP.SUPPLIERID AND  
                        SUPP.VENDORENTITYCODE = WPSTYLE.H2RWCO AND  
                        ESTYLE.STYLEUSERCODE = WPSTYLE.H2AICD AND  
                        WPSTYLE.H2SCNS = WPROD.H1SCNS AND  
                         WPROD.H1SCNS = WPSTYLE.H2SCNS AND  
                        WPSTYLE.H2SCNS = WPSKU.H3SCNS AND  
                        WPSTYLE.H2RWCO = WPSKU.H3RWCO AND  
                        WPSTYLE.H2AICD = WPSKU.H3AICD AND  
                        WPSKU.H3DINB = CAST (ESKU.SKUNUMBER AS DECIMAL) AND  
                        STYLE.STYLEID = ESKU.STYLEID AND  
                        ESKU.STYLEID = STYLEACTUALCOLOUR.STYLEID AND  
                        ESKU.ACTUALCOLOUROBJID = STYLEACTUALCOLOUR.ACTUALCOLOUROBJID AND  
                        STYLE.STYLEACTIVESTATUS = STYLEACTSTATUS.STYLEACTIVESTATUS AND  
                        ESKU.SKUACTIVESTATUS = SKUACTSTATUS.STYLEACTIVESTATUS AND  
                        ESKU.SKUID = SKUSIZE.SKUID AND SKUACTIVESTATUS NOT IN ('P', 'D') ;

And it throws the error as mentioned below.

(COALESCE(TRIM(FIRSTSIZE.SHORTSCALEVALUE) , '') || COALESCE(TRIM(', ' || SECSIZE.SHORTSCALEVALUE), '')) AS "SIZE",
                                                                                    *
ERROR at line 20:
ORA-12704: character set mismatch

But that is the syntax for coalesce and trim.

So what possible changes should I make to solve this issue.