output serial.read to client.print, and I am getting random signs

Hey I am trying to output, a serial.read() from a RFID reader to a string, so I can output i to a client.print.
if I do Serial.print(Serial.read()); it looks okey, in arduino serial monitor, but if I use client.print, it do not work.

I have tried this

char recieved =(char)Serial.read();
     inData += recieved; 
   
   Serial.print(inData);

it should look like this 0A007AA1AC but all I am getting is ž Ï ò µ and all other signs, and very random.

Do I need som kind of convertion, to understand the output from the serial.read()

#include <Ethernet.h>
#include <SPI.h>
byte mac[] = { 0x54, 0x34, 0x41, 0x30, 0x30, 0x31 };
char SH_serial;
char inData;

EthernetClient client;
char server[] = "92.144.244.134";
int  interval = 100;

/*function for serial conn*/
int readline(int readch, char *buffer, int len){
  static int pos = 0;
  int rpos;

  if (readch > 0) {
    switch (readch) {
      case '\n': // Ignore new-lines
        break;
      case '\r': // Return on CR
        rpos = pos;
        pos = 0;  // Reset position index ready for next time
        return rpos;
      default:
        if (pos < len-1) {
          buffer[pos++] = readch;
          buffer[pos] = 0;
        }
    }
  }
  // No end of line has been found, so return -1.
  return -1;
}


void setup() {

  Serial.begin(9600);
  Ethernet.begin(mac);

  Serial.print("IP Address        : ");
  Serial.println(Ethernet.localIP());
  Serial.print("Subnet Mask       : ");
  Serial.println(Ethernet.subnetMask());
  Serial.print("Default Gateway IP: ");
  Serial.println(Ethernet.gatewayIP());
  Serial.print("DNS Server IP     : ");
  Serial.println(Ethernet.dnsServerIP());
}

void loop() {
  // if you get a connection, report back via serial:
  
  static char buffer[12];
  //det er her vores funktion, som gøre rent i serial kommunikation
  if (readline(Serial.read(), buffer, 12) > 0) {
   
    //her sender vi koden over i en variable, som jeg sender til php og mysql
    //serveren med client.print, jeg skal havde lave et eller andet som buffer/
    //samler teksten op, inden den bliver sendt til serveren, måske skal det være to 
    //adskildte funktioner.w
    SH_serial = Serial.read();
    
   
//    inData is used in client.print at end of script
    char recieved =(char)Serial.read();
     inData += recieved; 
   
   Serial.print(inData);
   
    
  if (client.connect(server, 80)) {
    //Serial.println("-> Connected");
   
    // Make a HTTP request:
//inData goes here 
    client.print( "GET http://host.dk/anders/arduino_door/add_data.php?");
    client.print("serial=");
    client.print(inData);
    client.print("&&");
    client.print("temperature=");
    client.print( "12.3" );
    client.println( " HTTP/1.1");
    client.print( "Host: " );
    client.println(server);
    client.println( "Connection: close" );
    client.println();
    client.println();
    client.stop();
    
  }
  else {
    Serial.println("--> connection failed/n");
  }
  
  }
  
}
char inData;

     inData += recieved;

So, what does '0' + 'A' + '0' + '0' + '7' + 'A' + 'A' + '1' + 'A' + 'C' add up to?

Are you assuming that the + operator has some special meaning for characters? Even if it did (it does not), how many characters can you store in inData?