Sending data problem

Hello, I am trying to send data from my arduino due with a wifi shield to a php page on Aruba server for writing on mysql db.

I use the following http post call:

client.println ("POST /page.php HTTP/1.1");
client.println ("Host:" + host);
client.println ("User-Agent: Arduino/1.0");
client.println ("Connection: close");
client.println ("Content-Type: application / x-www-form-urlencoded; charset = UTF-8");
client.print ("Content-Length:");
client.println (urlupload.length ());
client.println ();
client.println (urlupload);
client.println ();

where urlupload results as:

urlupload = "t="+timestamplog+"&c="+(counter*Tmed)+"&v0="+valmed0+"&v1="+valmed1+"&v2="+valmed2+"&v3="+valmed3+"&v4="+valmed4+"&v5="+valmed5+"&v6="+valmed6+"&v7="+valmed7;

what I write has the form:
Timestamp Counter Val0 Val1 Val2 Val3 Val4 Val5 Val6 Val7
19/06/14 19:36:11 20 1631 1949 2161 2298 2312 2298 2335 1465

all goes well until the counter assumes the value 10000.
writing seems to be done, however on the db appear only a blank line.

What could be the reason? thanks