PaulS:
Having the instance name of the class be the same as the class name is a bad idea. Show some creativity in choosing a meaningful instance name.Using Strings is a bad idea. Learn to use c-style strings, instead.
fix = gps.read();Doesn't it matter that fix may not contain valid data?
dtostrf(latitudeX, 0, 7, latBuffer);
dtostrf(longitudeX, 0, 7, longBuffer);
In a field width of 0, show the digits before the decimal point, the decimal point, and 7 digits after the decimal point. Hmmm...
bro, I try with serial monitor not problem, but when i added sim800L the problem came up