run-time error 1004 - Why?

[Woftae]

Hi one & all, I have used this site many a time and it has helped me a lot, but this is my first post so if I have posted it incorrectly, I'm sorry.
I am also aware that there is probably a smarter way to do this code, but as I'm self taught it usually a matter of trial and error for me and
I'm tired of chasing my tail on this bit of VBA code, Can anybody tell me why this VBA code triggers a run-time error 1004

wshT.Range("I" & i).Formula = "=IF(LEN(CONCATENATE('SEO String Fillers'!C3,"" "",C" & i & ",'SEO String Fillers'!D3,"" "",D" & i & ","" "",B" & i & _
","" "",'SEO String Fillers'!E3,'SEO String Fillers'!F3<='SEO String Fillers'!B3,CONCATENATE('SEO String Fillers'!C3,"" "",C" & i & ",'SEO String Fillers'!D3,"" "",D" & i & _
","" "",B" & i & ","" "",'SEO String Fillers'!E3,'SEO String Fillers'!F3),IF(LEN(CONCATENATE('SEO String Fillers'!C3,"" "",C" & i & ",'SEO String Fillers'!D3,"" "",B" & i & _
","" "",'SEO String Fillers'!E3,'SEO String Fillers'!F3))<='SEO String Fillers'!B3,CONCATENATE('SEO String Fillers'!C3,"" "",C" & i & ",'SEO String Fillers'!D3,"" "",B" & i & _
","" "",'SEO String Fillers'!E3,'SEO String Fillers'!F3),IF(LEN(CONCATENATE('SEO String Fillers'!C3,"" "",C" & i & ",'SEO String Fillers'!D3,"" "",B" & i & _
","" "",'SEO String Fillers'!E3))<='SEO String Fillers'!B3,CONCATENATE('SEO String Fillers'!C3,"" "",C" & i & ",'SEO String Fillers'!D3,"" "",B" & i & _
","" "",'SEO String Fillers'!E3),IF(LEN(CONCATENATE('SEO String Fillers'!C3,"" "",'SEO String Fillers'!G3,"" "",B" & i & _
","" "",'SEO String Fillers'!E3))<='SEO String Fillers'!B3,CONCATENATE('SEO String Fillers'!C3,"" "",'SEO String Fillers'!G3,"" "",B" & i & _
","" "",'SEO String Fillers'!E3),CONCATENATE('SEO String Fillers'!C3,"" "",'SEO String Fillers'!G3,"" "",B" & i & ")))))"

 

[mole999]

1004 normally indicates something is misspelled or missing

If you use option explicit as the very first line of the sub and then compile that can help identify what might be an issue

 

[Woftae]

1004 normally indicates something is misspelled or missing

If you use option explicit as the very first line of the sub and then compile that can help identify what might be an issue

Thank you mole999 I will certainly give it a go.