Non empty string complained to be 'nil' in equality check

I have the below code
response = Net::HTTP.start(url.host, url.port) do
|http|
http.request(request)
end
exp_code = 450
if(response.code.to_i != exp_code)
raise StandardError, "Expected #{exp_code} Received
#{response.code.to_i}"
end
exp_msg = 'Blocked By Parental Controls'
puts 'Received status msg: #{response.message}'
if(response.message != exp_msg)
raise StandardError, "Expected #{exp_msg} Received
#{response.message}"
end

The received response is
HTTP/1.1 450 Blocked By Parental Controls^M
Date: Mon, 12 Apr 2010 10:28:15 GMT^M
P3P: policyref="(blah url)", CP="CAO DSP COR CUR
ADM DEV TAI PSA PSD IVAi IVDi CONi TELo OTPi OUR DELi SAMi OTRi UNRi
PUBi IND PHY ONL UNI PUR FIN COM NAV INT DEM CNT STA POL HEA PRE GOV"^M
cache-control: public,must-revalidate^M
Content-Length: 0^M
Connection: close^M
Content-Type: ^M
^M

The "puts" statement is printing
Received status msg: Blocked By Parental Controls

But the next statement for inequality check fails with
can't convert nil to string

However for a different case, where the response is
HTTP/1.1 200 OK^M
Date: Mon, 12 Apr 2010 10:28:29 GMT^M
P3P: policyref="(blah url)", CP="CAO DSP COR CUR
ADM DEV TAI PSA PSD IVAi IVDi CONi TELo OTPi OUR DELi SAMi OTRi UNRi
PUBi IND PHY ONL UNI PUR FIN COM NAV INT DEM CNT STA POL HEA PRE GOV"^M
cache-control: public,must-revalidate^M
Content-Length: 0^M
Connection: close^M
Content-Type: ^M
^M

and I have the ruby code as:
exp_msg = 'OK'
puts 'Received status msg: #{response.message}'
if(response.message != exp_msg)
raise StandardError, "Expected #{exp_msg} Received
#{response.message}"
end

Here there is no nil problem.
I have been breaking my head and don't have the slightest clue what is
happening. Can somebody please shed some light?

As you say, this line is giving you the error:

That error cannot happen on that line, unless response is nil, and based on how far you have gotten, that can't happen either.

I would suggest you add some more diagnostics to your code.

I know it can't happen, I have no clue. Just before the if statement I'm printing response.message it is printing the value.
Never encountered something so weird.

goddammit, i was fooled because the if statement was teh last statement in the code. The error didnt happen there at all. This code is a Ruby testframework code so it supposed to return a true/false and I was not returning, and that has caused the cruelly meaningless error message.
sorry for wasting everyone's time.