Hello Kenny,
When you are entering the APN please be sure that the case of each letter is exactly as shown per the providers info.
for example on the APN type if you insert [Default,mms,supl,hipri] it will not work or unless you lower case the "D" in default. The keyboard you are using may be attempting to capitalize the first letter in the line as it is assuming you are starting a new sentence.
Please let me know if this helps or if the issue still persists.
Thanks,