i have an AT&T version samsung galaxy s4 model 1337 bought in usa n being used in india with 4g sim i hv rooted the device and removed all att modules. i am unable to use mobile hotspot as whenever i turn on it reverts back wth message "no mobile data or invalid sim" . mobile data is actually on. i used hotspot control but doesnt help. there is a Mobile hotspot" app shown but not listed anywhee