Com a escassa referencia, creio que esse seria o significado. Esse negocio torna-se as vezes complicado.

i imagine that the uninteligible part was something that one party was worried about the other party and the second party is just telling him that it's not that, it's something else. as was mentioned before there isn't much context so it's hard to know.

Another possibility.

I like Amy's option above. Other options could be "it's not like that", "it's not like that at all", or "it's nothing like that".

It looks like the character is rambling...so I'd pick this as the translation...although the sentences and dialogue after that could change the best choice.

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Note added at 1 day15 mins (2007-01-10 12:41:14 GMT)
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After you added the context, I still feel this is the best option.
It seems the "other characther" says "There is something wrong here, otherwise you'd know how to tell me" ("Alguma coisa errada tem aí, se não você saberia contar."). He then proceeds to explain that "there's no such thing" (there is nothing wrong).