Gujarat State Road Transport Corporation [Gsrtc] — Student express pass not valid in bus

I have student express pass of route
Kadi-chatral-adalaj-sabarmati
As there are very less frequency of bus from Ahmedabad to kadi
First I trie to reach chatral in any bus (harij, mehsana, patan ) but in many bus they say student pass in not valid in this bus and they didn't give any reason for that. So I stuck either with giving money for ticket or standing at station and waiting for bus. Please someone help me with this.